Sea lions in the southern squid fishery (Part 2)

Last month we explored the overlap between the treasured New Zealand sea lion/ rāpoka and our southern squid fishery and mitigation steps to reduce interaction between the two. While significant advances in knowledge and investment in innovation has reduced sea lion fishing related mortality significantly, the situation remains complex, with additional factors at play.

Monitoring the population and disease

In the late 1990s when population monitoring became routine, there were increasing pup counts on the Auckland Islands. This was followed by a gradual decline in numbers after 2002, with an outbreak of Klebsiella pneumoniae— while at the same time, the fishing fleet was decreasing in size and capture rates of sea lions were declining. In 2014, the pup count dropped by 18% on the previous year and was the lowest count since 1995.

This triggered the development of the New Zealand sea lion/rāpoka Threat Management Plan (NZSL TMP). The NZL TMP details a five-year plan of targeted research, direct mitigation, and regular monitoring at all known sea lion breeding sites.

The plan also looks to better understand threats, including Klebsiella pneumoniae, nutritional and climate change stress, other environmental threats, and fishing impacts.

To date, Deepwater Group remains fully engaged in the TMP process and continues to ensure the squid fleet operates in alignment with Marine Mammal Operational Procedures and the Fisheries New Zealand SQU 6T Operational Plan.

Between 2014 and 2022, pup counts on the Auckland Islands stabilised.

However, in February 2023, DOC reported an estimated 25% decline in the expected number of pups on the island. DOC has commented that “this apparent drop was not associated with an increase in sea lion captures in fisheries around the Auckland Islands”. Figure !

In 2022 there were two sea lion captures in SQU 6T (Auckland and Campbell Island area), with 94% of the fishing events observed by government observers. Additionally, DOC noted that there weren’t any obvious outbreaks of Klebsiella pneumoniae. Neither were there any indications of widespread disease outbreaks at the colonies.

According to DOC, “One hypothesis is that the warmer than usual ocean temperatures may be affecting food availability, as some fur seal pup counts have had similar results this year”

Ocean temperature changes: 

According to MetOcean Moana project manager, Malene Felsing, “The fishing industry has been instrumental for the roll-out of the Moana Project , which is helping researchers, industry and government better understand oceanographic and water temperature changes across the whole of New Zealand’s Economic Exclusion Zone”.

Temperature sensors are deployed on fishing gear and temperature profile data are collected and automatically sent to a database to help improve marine forecasts and hindcast modelling, including forecasting the marine heatwaves that have been present throughout New Zealand waters for the last two years. The sensors are providing vital subsurface temperature data that we have never had, which has greatly

increased our understanding of our changing seas.

Pup counts on Stewart Island/Rakiura and the mainland: 

Despite the challenges faced by the Auckland Islands population, sea lions have begun to expand their range north from the subantarctic islands. Since the 1990s, breeding females have been returning to Port Pegasus in the southeast corner of Rakiura, and Otago Peninsula. These small but rapidly growing populations of sea lions on Rakiura and the mainland show the species is demonstrating adaptability and resilience.

In response to concerns about the impact of the fishery on the Auckland Islands sea lion population, the government and seafood industry have made significant efforts since the early 2000s to understand the effects of the fishery and develop new mitigation tools and approaches to reduce risks.

Looking forward

Over the past 20 years, the squid fishery has successfully reduced observed sea lion captures by around 90% since 2004 with a high degree of certainty, and the seafood industry remains committed to continued investment and partnerships to better understand risks to this taonga species.

Despite the stabilisation of these counts in recent years, the recent significant drop in New Zealand sea lion pup counts in 2023 is a major concern to deepwater quota owners.

The New Zealand seafood industry is committed not only to mitigating its own risks of harm but also to collaborating closely with researchers, DOC, and FNZ to investigate the causes of the decline, prioritize research and management efforts, and ultimately restore New Zealand sea lion populations to safe levels.

Additional information may be found at the links below.

www. deepwatergroup.org/wpcontent/uploads/2018/11/MMOP-Version-9-2.pdf 

mpi.govt.nz/dmsdocument/38189/direct 

moanaproject.org/recent-marineheatwaves

Figure 1: Total annual pup production estimates for New Zealand sea lions on the Auckland Islands, from 1994/95 to 2021/22. Covid interrupted the 2020/21 count. Black dot denotes 2021/22 minimumI estimate whilst the red dot denotes the adjusted estimate when a multiplier is applied.(source: Young MJ and Manno K (2022). Auckland Islands 2021/22 New Zealand sea lion field research report: CSP pup count. DOC)

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