Bycatch of New Zealand Wildlife

From GEOG397 Topics
Jump to: navigation, search


Bycatch Definition

Bycatch is the accidental catch of unwanted non-targeted species in the marine environment. This may occur when marine life becomes caught, entangled and drowned with current fishing methods such as nets or long-lines that are from either commercial or recreational fishers. Non-target species subject to bycatch in the New Zealand marine environment include Maui's dolphins, Hector’s dolphins, New Zealand Fur Seals, New Zealand Sea Lions and Marine Birds such as Shearwater and Albatross. Severe pressure has been placed on these species as a result of bycatch from fishing and topic of bycatch focusing on the six identified species is discussed throughout this page.


In New Zealand marine species are subject to the impacts of non-targeted fishing methods by trawlnets, gillnets and longlines. The harvesting of fish resources from the ocean has a large impact on indiscriminately catching marine life incident in the area. Populations of Dolphins, Sea lions, Seals and Seabirds have been negatively impacted as the populations have declined.

Hector's and Maui's Dolphin

Happy hector.jpg

New Zealand is home to the world’s smallest and rarest marine dolphins – the Hector’s dolphin. Hector’s dolphins are identified by a solidly built distinctive grey body with black and white markings, a gently sloping snout and a uniquely rounded dorsal fin. Hector’s dolphins grow to a maximum length between 1.4m - 1.6m in length and weigh between 40kg - 60kg. Hector’s dolphins are sub-categorized into two genetically distinct species. Dolphins found off the North Islands west coast are recognised as a sub-species, the Maui’s dolphin (Cephalorhynchus hectori maui) with numbers now estimated by DOC (Department of Conservation) at just 55 (Conservation, n.d.). Found off the coasts of the South Island is the Hector’s (Cephalorhynchus hectori hectori). During the 1970’s dolphin numbers were estimated at between 21,000 and 29,000 (Bird, n.d.) around New Zealand’s coastline. This number has declined dramatically to numbers estimated at approximately 7000. The Hector’s and Maui’s dolphins are recognized on the IUCN (International Union for the Conservation for Nature) Red List of threatened species (Nature, n.d.). Maui’s dolphins have the highest threat classification in New Zealand with a classification currently listed as critically endangered while Hector’s dolphins are listed as endangered (Nature, n.d.).

New Zealand Fur Seals

The scientific name for the New Zealand Fur Seal is Arctocephalus forsteri and is called Kekeno by the Maori people of New Zealand(Department of Conservation, n.d). The New Zealand Fur Seal is a large mammal, males have an average weight of 125kg and can grow up to 2m in length (Goldsworthy and Gales, 2008). The females are considerably smaller having an average weight between 30-50kg and growing up to 1.5m in length (Goldsworthy and Gales, 2008). Females reach maturity between the ages of 4-6 and begin breeding which occurs only once a year, being pregnant for about nine months. This continues till there death which is between 14-17 years (Goldsworthy and Gales, 2008). Male Fur Seal mature between 14-17 years and are polygynous breeders, which means that the males mate with other females during the mating season and return to the same location every breeding season. The New Zealand Fur Seal pups are born between November and January and the females stay close to the birth site for up to ten days. Within an hour the pups begin drinking, this can last up till 300 days. Around September the pups begin eating solid food and weaning begins (Goldsworthy and Gales, 2008). The pups are dependent on their mothers for a long time, which can result in future problems in terms of bycatch. The fur seals have external ears and hind flippers what rotate forward, this is one distinguishing feature from other seals (Goldsworthy and Gales, 2008). Breeding sites are widespread throughout New Zealand and the Sub-Antarctic Islands (Department of Conservation, n.d). The New Zealand Fur Seal is the world's best at diving, being able to dive deeper and longer than any other seal. Females Fur Seals can dive for up to nine minutes and to depths of 312m, while the males can dive up to 15 minutes and of depths up to 380m (Department of Conservation, n.d). Fur Seals can dive deeper and longer in winter and autumn, however, on average they only dive for 1-2 minutes at a time(Department of Conservation, n.d). This can be an issue because if they are in a net for over a certain amount of time Fur Seals will drown. When diving for food they dive deeper during the day although shallower at night and feed off the continental shelf. This is because during the day their prey typically migrates to deeper depths and migrates back to the surface during the night. Their diet included cephalopods, fish and birds, this various with the season and location (Bowen, 2012). Predators include killer whales, sharks, sea lions and leopard seals (Bowen, 2012).

New Zealand Sea Lions

The scientific name for the New Zealand Sea Lion is Phocarctos hookeri and is called Whakahao by the Maori people of New Zealand(Department of Conservation, n.d). The New Zealand Sea Lion is a large mammal; adult males are between 240-350cm in length and can weigh between 320-450kg while the females are smaller in length, measuring 180-200cm in and weigh 90-165kg(Department of Conservation, n.d). The female Sea Lions reach maturity at three years of age and have their first pup at the age of four, which continues up until their death producing a single pup every 1-2 years (Department of Conservation, n.d). Breeding occurs during the summer months with each pup being 70-100cm in length and weighing between 7-8kg. The pups are dependent on their mother for the first year of their life drinking their milk and protecting them from predators. Because the Sea Lion pups are highly dependent of their mother, this has consequences concerning bycatch, because if the mother is killed this leaves the pups motherless. The males hold their territory of breeding for 8-9 years (Department of Conservation, n.d). The life expectancy for females is on average 21 years. Around 95% of the population breeds on three beaches in the Auckland Island's (Spencer Davis, 2012). The high concentration of the population being in one place made the Sea Lion's vulnerable to a mystery disease killing over half of that year’s pups and approximately 20% of the adults in 2002 (Spencer Davis, 2012).

The majority of the breeding occurs on the Auckland Islands, the second largest population is on the Campbell Islands and there is some small populations around the coast of the South Island and Stewart Island (Forest and Bird, 2008). Sea Lions prey on a wide variety of species including fish, some types of sharks, octopus, rays and sometimes elephant seals and penguins (Gales, 2008). Predators include sharks, this is seen by the wounds evident on some Sea Lions, with pups being the most vulnerable to attacks.


New Zealand Shearwater and Albatross

The sooty shearwater (Puffinus griseus) is considered a medium to large seabird with a dark brown plumage and no obvious differences between the male and female (McGonigal, 2008). The Birds typically measure between 40 – 50cm with a 90-110cm wingspan. Other physical characteristics of this species tends to resembling that of a small albatross (McGonigal, 2008). These birds are distributed throughout the Pacific Ocean, being considered resident birds of New Zealand and the Falkland Islands. The breeding season occurs during October and pairs are committed to raising chicks for up to 110 days(McGonigal, 2008). The diet of the Sooty shearwater consists of mainly various squid species and fish. They are known to be deep divers, a behaviour developed in order to reach these food sources. The estimated population in 2011 was approximately 22 million pairs, but the recent decline in both adult population and breeding success has resulted in a population decrease (Tremblay, et al., (2006)). Albatross are wandering seabirds and are part of the Diomedeidae family. The "albatross" classification includes 21 species including the Wandering Albatross which has the largest recorded wingspan of any other extant bird, reaching up to 3.7m (Brooke, 2004). There is a global distribution of albatross, with speci found in both the northern and southern hemispheres (Tickell, 2000). Albatrosses have life long breeding partners. Chick development and rearing is a long and energetically expensive process. Due to this slow reproductive cycle these birds do not typically breed annually (Brooke, 2004). The life span of Albatross have been recorded to be up to 50 years with breeding maturity not being reached for several years (Brooke, 2004). The generalised diet of albatross tends to be a range of fish and squid and are known to fly thousands of kilometres, on strong wind currents in search for optimum feeding spots (Tickell, 2000).

The Pressures Associated With the Issue of Bycatch

The six species identified are subject to bycatch from the different methods of fishing. Each of the species identified occupy different habitats that require different methods in order for the fishery to successfully harvest the resource. These methods are set nets (Maui's and Hector's dolphins), trawl nets (New Zealand Fur Seals and New Zealand Sea Lions) and long-lines (Shearwater and Albatross).

Hector's and Maui's Dolphin

The biggest threat to the survival of the species has been identified by many sources as bycatch from fishery activities (WWF, Forest & Bird and DOC). Particularly significant is entanglements in gill nets, which dolphins become trapped and entangled in and drown. Gill nets are used by commercial, recreational and customary fishers and are responsible for more than 60% of all known Hector’s and Maui’s deaths where the cause of death is known (Bird, n.d.). Other vulnerabilities identified include; chemical pollution, vessel traffic, habitat modification and reproduction rates (WWF, n.d.). Hector's dolphins have slow reproduction rates, which causes problems for the species survival. Female dolphins only produce one offspring every 2-4 years and begin rearing calves when they are seven to nine years old. The slow rate of reproduction makes Hector's dolphin populations vulnerable to losses in populations from human impacts such as fishing.

New Zealand Sealions and Fur Seals

The pressure associated with the New Zealand Fur Seal and Sea Lion is the demand for food resources from the Ocean. This can be more specifically associated with the demand for Hoki (Blue grenadier) and Squid, which are primarly caught around the Sub-Antarctic Islands. Hoki and Squid have high demand from consumers that adds pressure to the fishing companies, so they have to developed methods for their nets to catch as much fish as possible in the quickest time possible. However, these methods can be very harmful towards non-targeted species and become ‘bycatch’ essentially a by-product from the fishing companies. Trawling is a type of commercial fishing technique which has very large nets that are dragged behind the fishing vessel for some time. The New Zealand Sea Lion and New Zealand Fur Seal are two of the main marine mammal’s which are subject to bycatch within New Zealand by the use of trawling. The New Zealand Sea Lion breeds mostly on New Zealand's Sub-Antarctic Auckland and Campbell Islands, this happens to also be where the main Hoki and Squid fisheries are based. The pressure associated with trawling is entanglement and drowning. This occurs because Sea Lions and Fur Seals can only be subject underwater for a certain amount of time. As the net continues to drag through the water the Sea Lion or Fur Seal can not go return to the surface for air and drowning or entanglement occurs, both of which resulting in the killing of the animal.

Forest and Bird (n.d) estimate that approximately 82% of Sea Lions killed in trawling are female, and are most likely to be pregnant, while also having a pup on shore. Therefore, this equates to three sea lion deaths (the mother, its unborn pup and the pup waiting on shore which will eventually starve to death)(Forest and Bird, n.d). Both Sea Lions and Fur Seals produce only a single pup every 1-2 years, this is another pressure associated with the species and also contributes to the declining population as reproduction is low and development to maturity takes a few years. The bycatch is outweighing the reproduction rates of the Sea Lion and in some places the Fur Seal (Bowen, 2012).

New Zealand Shearwater and Albatross


Under the umbrella of global fisheries, there are a few particular methods that are more detrimental to sea birds then others. These include long lining and trawling, which are both implemented in New Zealand waters (Peterson & Ryan, 2009) (Uhlmann & Jeschke, 2011). There are numerous marine species that have been identified as being threatened by these methods both in New Zealand and overseas and the impacts of continuation of the current bycatch rates would have extreme impacts on global marine ecosystems. Fisheries bycatch has increased the pressure placed upon marine bird species by increasing competition for food resources by exhausting target fish populations. In New Zealand, two species that have been identified as being significantly threatened by the long-lining industry are the Sooty Shearwater (Puffinus griseus) and the Royal Albatross. Long-lining is a technique used to catch Tuna, Halibut and has become increasingly controversial over the bycatch associated with it. Long-lining involves one long-line with branching lines attached to baited hooks(Moffitt,2008). This particular method has been identified as a major concern to the preservation of protected and endangered sea bird populations with increased bird mortality correlating with a growing long-lining industry (Anderson, et al., 2011) (Lewison, et al., 2004). The most significant issue with long-lining is how the birds become tangled and hooked by the lines, ultimately drown and are therefore dead before they even reach the vessel (Anderson, et al., 2011). The huge number of lines that finger off from the main line does mean that a high number of birds can be caught in a single yield. The Endangered status of many sea bird species in New Zealand does create an urgency to mitigate the mortality of birds in both long-lining and continue with the development of other, less threatening fishery practices. The figure on the right displays an example of catch rates in long line fisheries off the coast of South Africa, with very similar methodology used as those in New Zealand waters.

State of Environment

Maui's and Hectors Dolphin

Error creating thumbnail: Image type not supported

One of the areas of concern for the Hector’s dolphin is the slow rate of reproduction. Females reach maturity when they are aged between 7 to 9 years while for males it ranges from 5 to 9 years. It takes from 10 to 12 months after mating for the calf to arrive. The young arrive either in the later part of spring or the early summer. The calf takes approximately 2 years to be fully weaned. The calving interval is two to four years. The characteristics of reproduction mean that Hector’s dolphins, like many other small cetaceans, have a low potential for population growth. Maximum population growth rate has been estimated to be 1.8-4.9% per year, although the lower end of this range is probably more realistic (Slooten & Lad, 1991).

The populations of both Maui’s and Hector’s dolphin have declined from 1970 population levels. In 2002 Maui's dolphins were classified as a sub-species of Hector's dolphin. Previously, they had been known as the North Island Hector's Dolphin so estimates of populations were included as Hector’s dolphin. The Maui’s dolphin which is critically endangered has a population estimated at a current level of 55 (Conservation, n.d.). This is based on the collaborative works of DOC, The University of Auckland and The University of Oregon where research was conducted over the summers of 2010 and 2011. This is a decline from the previous estimate of 110 individuals which was estimated in the Hector’s Dolphin Threat Management Discussion Document 2007 produced by DOC and The Ministry of Fisheries (Conservation, n.d.). The below table shows the Incident Summary of DOC of Reported Maui’s dolphin mortality. Although many of the deaths were not assessed or determinable, 3 of the deaths are confirmed as human interactions which is equal to the known natural deaths

Error creating thumbnail: Image type not supported

Hector’s dolphins were once abundant throughout the South Island of New Zealand. The table below gives an estimate into the decline of the species to estimates of current levels.

Error creating thumbnail: Image type not supported

Incidents of Hector’s dolphin are also recorded by the DOC (Conservation, n.d.) and a summary of the period between3/07/2008 and 30/05/2013 is listed in the table below.

Error creating thumbnail: Image type not supported

New Zealand Sea Lions and Fur Seals

Since the 1890's the New Zealand Sea Lion has been protected when it's population started to decline, it is now considered the most threatened Sea Lion in the world (Forest and Bird, n.d). After having protection status for more than 100 years and being in a part of the world where the population is not that high, it should be expected that the population would increase. However, this is not the case and the main cause for this is being a New Zealand marine mammal Sea Lion are subjected to fishing bycatch.

The state of the environment regarding the New Zealand Sea Lion classified by the IUCN Red List is under the Threatened category, being mark as vulnerable. This means that the Sea Lion species is at high risk of becoming endangered in the wild, with a population of around 10,000 (Department of Conservation, n.d). Statistics from the Department of Conservation believed that the population was approximately 15,000 in the mid 1990s, although has declined to 9,000 in 2008(Department of Conservation, n.d). These statistics are based on the number of pups born each year, rather than the amount of adults, this is to give a future representation of the overall population. DOC also believes that the populations of Sea Lions around the Auckland Islands' nearly 80 per cent of the total populations could be functionally extinct by 2035.

Evidence for this statement is supported by Thompson and Abraham (2011) who conducted a study which was published by the Ministry of Fisheries. Thompson and Abraham (2010) observed that between 2006 and 2007 there was 15 sea lion captures on observed trawls in Sub Antarctic fisheries. A model then suggest an estimated 52 sea lion captures would have occurred across all trawls (observed and unobserved) and 105 Sea Lion interactions (the number that would have been caught had SLEDs not been used). Therefore, of this total there were 20 estimated captures and 74 estimated interactions for the Auckland Islands squid fishery on the Sea Lion population which is a decrease from the previous two fishing years. A map showing where the captures take place along with the number of pulls undertaken by each tralwer can be seen below (Thompson and Abraham, 2011)


Furthermore, in the past four years the Sea Lion pup population in the Auckland Islands has been declining, however, recent reports said that this year (2013) has been the first year the number has started increasing. It was reported that there was 1931 Sea Lion pups born this year, compared to 1684 last year (ScoopMedia, 2013).

Another breeding site, The Campbell Islands 'appears to be increasing slowly' and births here comprise about 20 per cent of the national total (Robertson and Chivers, 2011). In August 2013 the seasonal southern blue whiting fleet captured 19 male Sea Lions in fishing grounds more than 100 kilometres off the Campbell Islands and four were released alive. There were no captures reported by government observers the year before, however, fishing companies are obligated to report the captures and it is very hard to regulate whether the companies are reporting captures or not. Thompson and Abraham (2010) also state that all other fisheries the estimated captures have been declining over time. That in 2006-07 there were 14 estimated captures of Sea Lions in the Campbell Island southern blue whiting fishery, 12 in other (non-squid) trawl fisheries near the Auckland Islands, and five in all trawl fisheries on the southern end of the Stewart-snares shelf.

Also for the first time in 150 years Sea Lions began breeding again on the South Island coast in 1994, on the Otago Peninsula. The Otago Sea Lion population is currently small but estimated to reach 1000 animals by 2044, leading to issues of ‘marine protected areas, local fishing quotas and numbers management.’ This population has seen the return of the original female who has reproduced many daughters, grand-daughters and great-grand- daughters. Other small populations of breeding Sea Lions have recently begun to establish in various parts of the Stewart Island coastline.

The New Zealand Fur Seal is listed on the IUCN Red List as Least Concern, which means the population of the Fur Seals is thriving and there is no chance at the moment of extinction. Before the arrival of humans to New Zealand the population was estimated to be approximately 2 million. However, when European’ first settled the species was hunted for fur and oil. This put the species on the brink of extinction between the 1700’s-1800’s (Department of Conservation, n.d).

The population has recovered to a stable yet slowly increasing number of 50,000-60,000 which is seen as an underestimate by the Department of Conservation. Specifically in Otago there has been a 25% increase in population between 1982-1994 ((Department of Conservation, n.d)). The increase in population is also found in the Nelson/Marlborough area and in the Sub-Antarctic Bounty Islands (Department of Conservation, n.d).

New Zealand Shearwater and Albatross


The once thriving and healthy global Albatross populations have recently been presented with multiple stressors that has resulted in numerous albatross species being listed as endangered or protected (Brooke, 2004). The late maturity and slow breeding cycle of Albatross has made them especially susceptible to population depletion. The identified stressors that have contributed to the current plummet in populations include decreases in food resources as well as increased mortality of individuals due to particular fishing practices (Brooke, 2004). Studies have confirmed a link between the mortality in the long-lining industry and the changes in the Southern ocean populations of Albatross (Fig 1). The increased fishing activity in the Southern ocean has been linked to the recent decrease in the respective populations of Wandering and Royal Albatross and have triggered current research to try and secure the connection between fisheries and these declines in order to encourage change in the industry (Tuck, et al., 2001). Sooty Shearwater, even if not at the same vulnerability as the Albatross, increased occurances of Shearwater mortality through fisheries has made the 44 million strong bird population a topic of concern (Brooke, 2004). The activity surrounding fishery vessels on the water have been thought to be attracting the birds to the lines, ultimately resulting in bird mortality (Uhlmann & Jeschke, 2011). Although the Shearwater bycatch has been thought to have increased, the population does have much more potential to restore itself when compared to the Albatross due to it’s higher numbers and more frequent annual breeding cycle (McGonigal, 2008).

Response of Key Stakeholders

Maui's and Hectors Dolphin

The preservation of Hector’s and Maui’s dolphin has taken interest of many interested groups and organizations gaining both national and international recognition.

Government Response

Government attention has been focused primarily through the efforts of the Department of Conservation in conjunction with the Ministry of Agriculture and Fisheries now the Ministry for Primary Industry’s. Together they have released The Hector and Maui Dolphin Threat Management Plans (TMP) in order to preserve the species. The government’s vision statement (Conservation, n.d.) for the management of Hector and Maui dolphin’s states: “Hector’s and Maui’s dolphins should be managed for their long - term viability and recovery throughout their natural range” (Government, et al., n.d.). The TMP 2008, was developed setting out goals to; Ensure that the long term viability of Hector’s and Maui’s dolphins is not threatened by human activities; Further reduce impacts of human activities as far as possible, taking into account advances in technology and knowledge, and financial, social and cultural implications (Government, et al., n.d.). As part of on-going management the TMP is routinely reviewed. A review of the Maui’s portion of the TMP (2008) reconsiders strategies for management and/or research that will support the recovery of the Maui’s dolphin population, the latest review being completed in 2012 having been brought forward from 2013, while the Hector’s review is scheduled for 2014. The review processes aim to reassess management measures based on updated information on the dolphin species population, the human-induced threats they are exposed to, and their vulnerability to those threats (Government, et al., n.d.).

National Non-Government Organization Response

Other local stakeholders outside government agencies include Forest and Bird and Seafood New Zealand although other advocacy groups share concerns for the continued survival of the species. These two organizations accept the pressures that have been placed upon the species by human influences but the interests of the organizations are reflected by strategies suggested / lobbied for in order to ensure the species survival. Forest and Bird take a proactive approach to the conservation of Hector’s and Maui’s dolphin. A submission made by Forest and Bird to the Ministry of Agriculture and Fishery April 2012 conveys that Maui’s dolphin or any other marine mammal has full protection under the Marine Mammal Protection Act 1978 and that none should be killed in any fishing operation, either accidentally or deliberately (Bird, n.d.). In the submission Forest and Bird makes six key recommendations in order to protect the critically endangered Maui’s dolphin which are;

• “Best available information is used to advise the Minister, including scientific research which has been carried out on the closely related Hector’s dolphin

• Immediately ban all gill nets in all areas where Maui’s dolphins are found (out to the 100 m depth contour). At a minimum extend the current gill net ban from Pariokariwa Point south to Hawera and offshore to the 7 nautical mile boundary.

• Immediately ban all inshore trawls operating in all areas where Maui’s dolphins are found (out to the 100 m depth contour). At a minimum extend the current trawl ban from Pariokariwa Point south to Hawera and offshore to the 7 nautical mile boundary.

• Immediately ban all gill nets within all harbours (Kaipara, Manukau, Raglan, Aotea, & Kawhia) along the west coast of the North Island which are currently un-protected

• Immediately increase observer coverage on all gill net and inshore trawl vessels operating outside of the current and soon to be protected areas to 100%.

• Protect the important link and future connectivity between the North Island Maui’s and the South Island Hector’s dolphin populations by protecting the corridor across the Cook Strait between Farewell Spit and Taranaki” (Bird, n.d.)..

Seafood New Zealand firmly supports the preservation of Hector’s dolphin and the subspecies Maui. They advocate urgent, targeted and scientifically based measures to target efforts where Maui’s dolphins exist. They cite 'the facts' claiming that no Maui’s dolphin has ever been confirmed as entangled in a set net outside the fishing restricted protection zone that was established in 2003 (Zealand, n.d.). They also state that since records began in 1921 there has not been a single report of a Maui’s being caught in a trawl net (Zealand, n.d.). Other factors which Seafood New Zealand express is that no Maui’s dolphin has been recorded as entangled in any fishing net since 2002 (Zealand, n.d.). Seafood New Zealand claims that this has not stopped a campaign to make it appear that Maui’s deaths from fishing are frequent and observed. They also advocate that other factors must be taken into account for Maui mortalities such as Toxoplasmosis which is a land based disease from animals such as cats and humans which has been confirmed by post mortems according to Seafood New Zealand (Zealand, n.d.). There is practically no research to protect Maui’s against this disease. Seafood New Zealand has also noted the discrepancy of reported deaths between agencies (Zealand, n.d.).

Error creating thumbnail: Image type not supported

This compares the online DOC Incident Database data in the left column, with the NABU report to the IWC Scientific Committee figures in the right column. They are gathered from the same source data so, should be the same but are not. This could indicate that the actual numbers of dolphin mortalities as by-catch are unknown.

International Non-Government Organization Response

Finally the Maui's and Hector's dolphin has attracted international attention. Organizations such as WWF and IUCN (International Union for Conservation of Nature). WWF categorizes the Maui's dolphin as a sub-species of the Hector's dolphin and estimates that their population as totaling 100 (WWF, n.d.). They express that the species is vulnerable to a large number of different threats that include chemical pollution, habitat modification and vessel traffic but document the main threat to the species survival is by-catch in net fisheries especially the threat of gill nets. WWF estimate that the population of Hector's has declined to approximately a third to a half of 1970 populations, possibly from the impacts of by-catch on the species from gill net entanglements (WWF, n.d.). Actions taken by WWF-New Zealand include advocating for increased protection for Hector's and Maui's dolphin by means of government fisheries and conservations decisions. Other actions include support for communities and school awareness programmes for Maui dolphins currently and also in development a South Island programme. It is also involved in carrying out research that aids to inform management decisions. Part of this involvement includes documenting public sightings via a website and toll-free number. The objectives WWF lays out from Hector's and it subspecies Maui's are that threats have been reduced so that the species are able to begin increasing in abundance, extending the range of Maui's dolphin and reducing the isolation of Hector's dolphin populations (WWF, n.d.). Although WWF are locally involved the majority of their work to protect whales and dolphins take place within the context of the International Whaling Commission (IWC) (WWF, n.d.).


Actions Taken To Protect Maui's and Hector's Dolphins

The main solution that has been proposed is the banning of set nets in locations which Hector’s and Maui’s dolphin frequent which can be seen in the image to the right. Bans on set nets have been put in place for the protection of the Maui’s and Hector’s dolphin from 2008 administered by the Ministry for Primary Industry (Industries, n.d.) that cover six large areas throughout New Zealand’s coastal waters which are:

West Coast North Island - Set Net Prohibition Set netting is prohibited between Maunganui Bluff north of Kaipara Harbour and Pariokariwa Point north of New Plymouth – offshore to seven nautical miles. Set netting is prohibited at the entrance of the Kaipara, Manukau and Raglan Harbours as well as at the Waikato River entrance.

Waikato River Drift- Net Prohibition Drift netting is prohibited in any part of the Waikato River.

Taranaki Area - Set Net Prohibition Commercial and recreational set netting prohibited 2nm from Pairokariwa point to Hawera (South of the end of Beach Road).

East Coast South Island - Set Net Prohibition Set netting is prohibited between Cape Jackson in the Marlborough Sounds and Slope Point in the Catlins ─ offshore to four nautical miles.

South Coast South Island - Set Net Prohibition Set netting is prohibited between Slope Point in the Catlins and Sand Hill Point east of Fiordland ─ offshore to four nautical miles. Set netting is prohibited the whole of Te Waewae Bay.

West Coast South Island - Set Net Prohibition From Farewell Spit Lighthouse in the north to Awarua Point north of Fiordland:

• Recreational set netting is prohibited offshore to two nautical miles

• Commercial set netting is prohibited offshore to two nautical miles between 1 December and 28 February

Other limitations that have been put in place for the protection of the Maui’s and Hector’s Dolphin cover areas that are trawled by commercial fisheries and prohibit that activity in these areas. These bans cover three areas in New Zealand which are;

West Coast North Island - Trawl Prohibition Trawling is prohibited between Maunganui Bluff north of Kaipara Harbour and Pariokariwa Point north of New Plymouth – offshore to two nautical miles, to four nautical miles between Manukau Harbour and Port Waikato.

East Coast South Island - Trawl Restriction Trawl gear is restricted offshore to two nautical miles between Cape Jackson in the Marlborough Sounds and Slope Point in the Catlins.

South Coast South Island - Trawl Restriction Trawl gear is restricted offshore to two nautical miles between Slope Point in the Catlins and Sand Hill Point east of Fiordland.

However the measures that were put in place have been the subject of a legal challenge by a number of commercial fishing groups that requested a judicial review to overturn the Government’s new fishing regulations (Bird, n.d.). From 2008 until the decision was made the court granted interim relief, allowing the continued fishing off the West Coast of the North Island and parts of the East and South coasts of the South Island until proceedings in the High Court were completed. The case was heard in the High Court in Wellington in May 2009. A final decision was announced by the then Minister of Fisheries nearly two years later in March, 2011. As a result, fishing continued in the exempted areas for nearly two years. While some parties say these measures go too far others disagree and would like preventative measures to go further.

New Zealand Sealions and Fur Seals

Government Response

The government responded to the capture of Sea Lions by requesting that vessels trial Sea Lion Exclusion Devices (SLEDs) to reduce bycatch. Since 2007, all vessels in the Auckland Islands fishery have been equipped with SLEDS (New Zealand Ministry for Primary Industries, n.d) A SLED is a grid fitted in the net before the cod end, with the spacing between the bars designed to prevent sea lions passing through (Dragonfly Science, n.d). The grid is angled so that the Sea Lions are directed upward towards a hole in the top of the net, and they are able to escape from the net (Dragonfly Science, n.d). A Sea Lion exclusion device can be seen below showing how the Sea Lion can escape from trawling nets when used (Ministry of Primary Industries,n.d).

Error creating thumbnail: Image type not supported

Also the proportion of vessels in the Auckland Island squid fishery with government observers also increased over the years, providing independent reports of bycatch based on the observation of Sea Lions captured rather than computer models. In the 2013 season the observers' coverage was of 86 per cent of tows (New Zealand Ministry for Primary Industries, n.d).

Other methods in which the government responded was the use of a modelling system to gage a fishing related mortality limit (FRML) for each fishing season. If the limit of bycatch was predicted to be exceeding, the Minister of Primary Industries may close the fishery. The last time the fishing related mortality limit was exceeded was in 2000 and there was a number of closures in the 1990s (New Zealand Ministry for Primary Industries, n.d).

For the New Zealand Fur Seals the response to the bycatch effects is that in 2000 a 16 million hectare marine park was created on the Eastern part of the Macquarie Island by the Tasmanian government. This has recently been extended to Macquarie Island natural reserve by 3 nautical miles surrounding the island by the New Zealand government. Because the population of the New Zealand Rur Seals is stable and increasing there has been minimal response to the bycatch by the government and other organisations compared to the Sea Lion populations (Department of Conservation, n.d).

National Non-Government Organization Response

Forest & Bird would like the squid fisheries to stop using trawling nets and try alternative fishing methods, such as jigging. This method will not harm Sea Lions, Fur Seals or another other types of fish from the Sub-Antarctic waters where Sea Lions and Fur Seals feed (Forest and Bird, n.d).

International Non-Government Organization Response

The World Conservation Union this year changed the Sea Lions threat status by listing them as being in decline (Forest and Bird, n.d). The change of World Conservation status to a decreasing in the population allows members of the public to be able to acknowledge that this species is under threat and therefore, putting more pressure of commercial fishing rules and regulations.

New Zealand Shearwater and Albatross

There has been a lot of research put into finding new fisheries methods in order to attempt to solve or minimise the issue of seabird bycatch. The co operation between scientific faculties and New Zealand /international authorities is vital to the progress in creating regulations and scientifically supported changes within global fisheries.

Government Response

New Zealand government agencies, such as the Department of Conservation and the Ministry of Fisheries, have been working together in order to publish the ‘Conservation services levi’. These legislations require the New Zealand fisheries industry to financially fund research being undertaken to develop both bycatch (West, et al., 1991). There has also been increased pressure on the government to improve the policing of bycatch limits as well as introducing harsher penalties for those who do not abide to the strict regulations

National Non-government Organization Response

New Zealand Forest and Bird have been campaigning against the current regulations surrounding long lining fisheries in order to attempt to protect the albatross populations in New Zealand waters. By evoking seasonal and area closures as well as "night setting" the non-government organisation has been increasing the awareness of the issue and has been encouraging both the public and other organisations to get involved in promoting new regulations that would decrease the bycatch of not only the albatross but other vulnerable sea bird species(Forest and Bird,2011).

International Non-Government Organization Response

There have been suggestions about finding ways to discourage the presence of birds around fishing vessels in order to prevent them being caught up in the gear. It was proposed that the use of shark liver oil as a deterrent decreased both the number of birds present as well as the number of bait dive made (Pierre & Nordan, 2006). It has also been suggested that encouraging fishing during poor light conditions would be an effective way of mitigating bird bycatch. A study carried out on the long line hake fisheries off the coast of South Africa indicated that demersal fisheries have a dramatically higher albatross catch rate compared to those who drop lines during the night and harvest the catch early morning (Peterson, et al., 2009).International organisations such as the World Seabird Union have played a part in gathering data surrounding the bycatch of seabirds in New Zealand waters and has provided resources to attempt to raise awareness of the issue to both New Zealand and international parties (Irons, 2007).

Case Study

Maui's and Hectors Dolphin

Much effort has been taken to achieve a greater understanding of the Hector’s and Maui’s dolphin from the scientific community with work focusing on population totals, population distribution for the purposes of supporting decision making in appropriate placements in protection areas. From the findings, restrictions on commercial gill nets currently in place currently protect 60% or less of the dolphin population for only 3 mo of the year (Rayment, et al., 2011). The case work in this study suggests that a 6nmi offshore boundary in the protected area would enhance protection measures (Rayment, et al., 2011) which would in the case of the South Island’s west coast reduce by catch level’s to almost zero. The reduction of by catch levels to near zero levels leaves s a greater range of management options open for the future (Slooton, 2007). “If management intervention is delayed until the species or ecosystem has gone beyond the point of no return, even the most rigorous management of remnant areas will be too little, too late” (Slooton, 2007).

New Zealand Shearwater and Albatross

There are various species of albatross that are being impacted by the intensity of modern commercial fisheries, but in regard to New Zealand's conservation priorities the Royal Albatross is of particular concern. The small population numbers combined with slow juvenile development and late sexual maturity makes this particular bird incredibly susceptible to the negative impacts of New Zealand long lining industries. Discussions around seasonal limitations and regulations established around the breeding cycle of these birds has been suggested as a viable option(Forest and Bird,2011).


Human influence extends beyond the boundaries of the terrestrial environment. The demand for marine resources for human consumption has placed great pressure, not just on the targeted populations, but also on the associated ecosystems and foodchains. The interactions from fishing methods that are implemented such as gill nets, trawling and long-lining have negatively impacted the species outlined through this article. These pressures have altered the state of the environment to a point where a response must be undertaken. The case studies stated previously are just a minute proportion of the species currently being impacted by the global fishing industries and their disregard for the unsustainable nature of their practices. There has, however, been a recent increase in awareness of the issues severitywith and both government organisations and privately funded groups taking action.Some of the suggested approaches have been as dramatic as banning specific fishing methodology in large areas of the countries coastal waters. Without these responses, undoubtedly the state of these species and the environment which they reside in may diminish and could result in the worst case scenario - extinction of multiple marine species.


Maui's and Hector's Dolphin

Bird, F. a., n.d. Hectors and Maui's dolphin. [Online] Available at: [Accessed 16 9 2013].

Bird, F. a., n.d. Hector's Dolphins: Legal Challenge. [Online] Available at: [Accessed 23 9 2013].

Bird, F. a., n.d. Hector's dolphins: Threats. [Online] Available at: [Accessed 9 9 2013].

Bird, F. a., n.d. Submission: Interim set net measures to. [Online] Available at: [Accessed 16 9 2013].

Conservation, D. o., n.d. Conservation General Policy - 13. Conservation Management Strategies and Plans. [Online] Available at: [Accessed 9 9 2013].

Conservation, D. o., n.d. Hector's and Maui's dolphin Estimate. [Online] Available at: ) [Accessed 9 9 2013].

Conservation, D. o., n.d. Hector's and Maui's dolphin incident database. [Online] Available at: [Accessed 22 9 2013].

Conservation, D. o., n.d. Mau's Dolphin. [Online] Available at: [Accessed 16 9 2013].

Government, N. Z., Industrys, M. f. P. & Conservation, D. o., n.d. Review of the Maui's dolphin Threat Management Plan. [Online] Available at: 16/9/13 [Accessed 9 9 2013].

Industries, M. f. P., n.d. Maui's and Hector’s dolphins. [Online] Available at: [Accessed 22 9 2013].

Nature, I. U. f. C. o., n.d. Cetacean update of the 2008 IUCN Red List of Threatened Species. [Online] Available at: [Accessed 16 9 2013].

Rayment, W. et al., 2011. Distribution of Hector’s dolphin (Cephalorhynchus hectori) off the west coast, South Island, New Zealand, with implications for the management of bycatch. Marine Mammal Science, Volume 27.

Slooten, E. & Lad, F., 1991. Population biology and conservation of Hector’s dolphins. Canadian Journal of Zoology, Volume 69, pp. 1701-1707. Slooton, E., 2007. Conservation management in the face of uncertainty: effectiveness of four options for managing Hector’s dolphin bycatch. ENDANGERED SPECIES RESEARCH, Volume Vol. 3, p. 169–179.

WWF, n.d. Hector'. [accessed 9/9/13][Online].

Available at: [Accessed 9 9 2013].

Zealand, S. N., n.d. Why the International Whaling Commission will not save Maui’s Dolphins. [Online]

Available at: [Accessed 16 9 2013].

New Zealand Fur Seals and Sealions

Forest and Bird., n.d Forest and Bird condemn 40% rise in sea lion quota. [online]. Available: [25 September 2013].

Bowen, W.D., 2012. A review of evidence for indirect effects of commercial fishing on New Zealand sea lions (Phocarctos hookeri) breeding on the Auckland Islands. Deepwater Group Ltd, Department of Conservation’s Conservation Services Programme [online]. Available: [2 October 2013]

Thompson, F. N., & Abraham, E. R., 2011. Estimation of the capture of New Zealand sea lions (Phocarctos hookeri) in trawl fisheries, from 1995–96 to 2008–09. New Zealand Aquatic Environment and Biodiversity Report No. 66. 25

Dragonfly Science. n.d. Sea lion bycatch in New Zealand trawl fisheries. [online]. Available: [25 September 2013].

Department of Conservation., n.d. Facts about fur seal. [online]. Available: [25 September 2013].

Spencer Davis, L. 2012. 'Seals - New Zealand sea lion', Te Ara - the Encyclopedia of New Zealand. [online]. Available: [25 September 2013].

ScoopMedia., 2013. Auckland Island Sea Lion Pup Count Up for Second Year. [online]. Available: [2 October 2013].

Roberston, B.C. & Chilvers, B.L., 2011. The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes. Mammal Review doi: 10.1111/j.1365-2907.2011.00186.x

Crawley, M.C. & Wilson, G.J., 1976. The Natural History and Behaviours of the New Zeland Fur Seal (Arctocephalu forsteri). Tuatara, 22 (1), [online]. Available : [25 September 2013].

Goldsworthy, S. & Gales, N. (IUCN SSC Pinniped Specialist Group) 2008. Arctocephalus forsteri. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. [online]. Available: [01 October 2013].

Chilvers, B.L. & Wilkinson, I. (2011) Research to assess the demographic parameters of New Zealand sea lions, Auckland Islands: Draft Final Report. Aquatic & Threats Unit, Conservation Services Programme, Department of Conservation, Coffs Harbour, Australia,

Ministry of Primary Industries., n.d. Squid (SQU6T) – Final Advice Paper. [online.] Available: [1 October 2013].

Gales, N., 2008. Phocarctos hookeri. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. [online]. Available: [01 October 2013].

Department of Conservation., n.d. Facts about sea lion. [online]. Available: [25 September 2013].

Marine Birds

interactive, s., 2011. Forest and Bird New Zealand. [Online] Available at:[Accessed 1 october 2013].

Irons, D., 2007. World Seabird Union - New Zealand Seabird Bycatch Data. [Online] Available at:[Accessed 30 september 2013].

Anderson, O. et al., 2011. Global seabird bycatch in global longline fisheries. Endangered Species Research, 14(2), pp. 91-106.

Brooke, M., 2004. Albatrosses and Petrels Across the World. London: Oxford University Press.

Lewison, R., Crowder, L., Read, A. & Freeman, S., 2004. Understanding impacts of fisheries bycatch on marine megafauna. Trends in Ecology and Evolution, 19(11), pp. 598-604.

McGonigal, D., 2008. Antarctica: Secrets of the Southern Continents. 220 ed. New York: Firefly Books. Peterson, S. et al., 2009. Seabird bycatch in the demersal longlne fishery off southern Africa. African Journal ofMarine Science, 31(2), pp. 205-214.

Peterson, S. L. H. M. & Ryan, P. U. L., 2009. Seabird bycatch in the pelagic longline fishery off southern Africa. African Journal of Marine Science, 31(2), p. 191.

Pierre, J. P. & Nordan, W. S., 2006. Reducing Seabird Bycatch in Longline Fisheries using a natural olfactory deterrent. Biological Conservation, 130(3), pp. 405-415.

Tickell, W., 2000. Albatrosses. Sussex: Pica Publishing.

Tremblay, S. S. et al., (2006). Migratory shearwaters integrate oceanic resources accross the pacific ocean in an endless summer". PNAS, 103(34), pp. 12799-12802.

Tuck, et al., 2001. Modelling te impact of Fishery Bycatches on Albatross Populations. Journal of Applied Ecology, 38(6), pp. 1182 - 1196.

Uhlmann, S. S. & Jeschke, J. M., 2011. COmparing factors associated with total and dead sooty shearwater bycatch in New Zealand trawl fisheries. Biological Conservation, 144(6), pp. 1859-1865.

West, I. F., Molloy, J., Donoghue, M. f. & Pugsley, C., 1999. Seabirdand marine mammal bycatch reduction through fishing industry funded research: The New Zealand conservation services Levy program. Marine Technology Society, 33(2), p. 13.