Draft Squid 6T Operational Plan

Consultation background

New Zealand sea lions are part of our heritage, and we want to make sure they are around for future generations. Once abundant throughout the country, they were hunted in the 1800s to near extinction, but have recovered to a point where they are now classified as Nationally Vulnerable.

There are a range of threats to sea lions including disease, environmental fluctuation, and fishing. We're working together with the Department of Conservation on implementing a long term plan - called the New Zealand sea lion/rāpoka Threat Management Plan to address these threats.

There remain a range of threats to sea lions outside of fishing including disease and environmental factors. However, there is some cause for cautious optimism. The evidence is telling us the measures in place to manage fishing impacts are effective. We need to make sure that continues.

Auckland Islands female sea lion population over time

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This figure shows the estimated abundance trend for the New Zealand sea lion female breeding population at the Auckland Islands. It is based on using sea lion pup counts to estimate pup production, which then provides an index of total population size. At the Auckland Islands, a large proportion of the sea lion population has been tagged to allow for annual resighting information to be collected. A Bayesian demographic population model has been developed which incorporates all available data including pup counts, age distribution data from lactating females, and tag-resight data to inform estimates of critical demographic rates.

The model structure allows the underlying demographic rates responsible for the 3 observed population changes over the last 3 decades. There was rapid growth from 1990 to 2000, then a decline between 2000 and 2009. Sea lion pup production has increased slightly in recent years, and outputs of the updated model suggest that the population may be stabilising.

 

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One of the key breeding sites is around the subantarctic Auckland Islands, which is also where commercial fishing vessels operate each year looking to harvest squid. This fishery brought home some $56.6 million export revenue to New Zealand last year.

We keep a close eye on this fishery, called Squid 6T, so that any impact on sea lions from fishing is minimised. This year 95% of all fishing effort has been monitored by on-board Fisheries New Zealand observers.

In addition, all vessels operating in the area use Sea Lion Exclusion Devices or SLEDs in their trawl nets. These work by allowing most sea lions that swim into the net to escape.

SLEDs net infographic animation

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The most important mitigation initiative developed and used by the fishing industry to mitigate impacts on sea lions is the Sea Lion Exclusion Device (SLED). SLEDs are designed to guide actively swimming sea lions to an escape hole to exit the net. From their introduction in 2000 to 2007, the design of SLEDs was regularly adjusted to improve performance. In 2007 the ‘Mark 3/13' design became the agreed SLED standard for SQU6T. SLEDs are considered to be effective at allowing most sea lions to escape from the trawl net and survive.

The use of SLEDs is not currently regulated, however, under the Operational Plan, all vessel operators that intend to fish for squid in SQU6T agree to deploy SLEDs on all tows. Vessels carry at least 2 SLEDs which are inspected at the start of every season by a registered net making company to make sure they meet specifications. Fishery Observers on vessels in the SQU6T fishery also audit SLED specifications, confirm that SLEDs are in good working order and are being deployed in the correct manner.

 

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We have seen encouraging results from the use of SLEDs, but there have historically been some question marks over how effective they have been at ensuring sea lions survive. In particular it has been difficult to account for the sea lions that may have escaped trawl nets through SLEDs but might have died as a result of being in the net or any that drowned in the net and may have fallen out.

Fisheries New Zealand conducted a comprehensive research programme to get to the bottom of this issue, to allow us to estimate the effectiveness of SLEDs with more confidence.

As a result we not only know that SLEDs allow the majority of sea lions to escape and survive, but we can characterise what might happen to a sea lion that swims into a trawl net.

Approximately 20 sea lions swim into trawl nets each year.

Midwater trawl infographic

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88% that enter a midwater trawl net swim out, 12% drown in the net and do not swim out. Of the 88% that swim out 5-7% run out of air before the reach the surface and subsequently drown. Of the 12% that drown in the net, 5% are estimated to fall out before the net is hauled.

 

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Our scientific models estimate that a sea lion that encounters a fishing vessel is more likely to go into a midwater net than a bottom trawl net, but also that once a sea lion goes into the net it is more likely to exit a midwater net and survive. For this reason, the estimated effectiveness of the SLED is higher for midwater nets, but the overall risk to sea lions is almost equal between the 2 fishing methods.

The research shows that for every 3 that are observed captured, we estimate a fourth sea lion died that wasn't able to be seen.

From this information, we know that fishing in SQU6T is having a very low impact on the sea lion population – over the last 5 years, it is estimated that fewer than four sea lions were killed in this fishery each year on average which is estimated to be having less than a 1.5% impact on the population in the long term.

Bottom trawl infographic

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57% that enter a bottom trawl net swim out, 43% drown in the net. Of the 54% that swim out, 5-7% run out of air before the surface and subsequently drown. Of the 43% that drown in the net, 5% are estimated to fall out before the net is hauled.

 

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Estimated annual sea lion deaths and fishing effort diagram

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The scale on the left-hand axis of the chart relates to the solid blue line which plots the estimated number of total sea lion deaths each year from 1992/93 to 2016/17. The estimated number of total deaths has declined substantially from a high of over 160 deaths in the early 1990s to a low of under 10 sea lion deaths per year since 2008/09. The scale on the right-hand axis of the chart relates to the solid orange line which plots the actual annual fishing effort as number of trawl tows. This has also declined over time from a high of just under 5,000 trawl tows in Squid 6T in the early 1990s to an average of under 2,000 trawl tows per year since 2008/09.

 

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Of course, we would be happy if there were no sea lions being caught by fishing vessels. All food production, whether on land or at sea, has an impact on the environment. In this case, our job is to strike the right balance between food production and the impact fishing can have on sea lions. If we know fishing is having too big of an impact on the population, the Minister will take action, including closing the fishery. We wanted your help finding the right balance to manage this fishery.

We sought people's views on:

• making the use of SLEDs mandatory across the fishery
• setting a minimum observer coverage target of 90%
• putting a limit on the number of sea lions that can be accidentally caught in the fishery before it is automatically shut down. There are 3 options in the paper which equates to a 2.5%, 5% or 10% impact on the sea lion population.

Consultation document

• Discussion document [PDF, 985 KB]

What was proposed?

Interactions between New Zealand sea lions and the squid fishery around the Auckland Islands are managed through the Squid 6T Operational Plan, which sets out a range of measures to avoid, remedy, or mitigate the effect of fishing-related mortality on the New Zealand sea lion population.

The primary regulatory measure in the Squid 6T Operational Plan is a fishing-related mortality limit which is the maximum number of sea lion mortalities that may occur in the fishery annually. Should the limit be reached, the fishery is closed immediately.

Fisheries New Zealand proposed a new, more direct, approach to monitor against the mortality limit based on observed sea lion captures. This was made possible by new research which better quantified and reflected the uncertainty in the level of interactions of sea lions with squid fishing and the effectiveness of SLEDs.

Full details were in the consultation document.

More information

• Spatial assessment of fisheries risk for New Zealand sea lions at the Auckland Islands [PDF, 4.6 MB]
• Population effects of New Zealand sea lion mortality scenarios in squid fishery at the Auckland Islands [PDF, 1.2 MB]
• Desktop estimation of New Zealand sea lion cryptic mortality in trawls using SLEDs [PDF, 593 KB]
• Simulating sea lion dives to assess the probability of post-exit drowning for sea lions exiting SLEDs [PDF, 2.7 MB]
• Threat Management Plan for New Zealand sea lions - DoC website
  
• Quantitative Risk Assessment of Threats to New Zealand Sea Lions - AEBR 166 [PDF, 6.6 MB]
• Spreadsheet OIA19-0509 Telemetry Data [XLSX, 1.2 MB]
  • This spreadsheet contains satellite telemetry data produced from the Bayesian SSSM output and provided as part of Fisheries New Zealand project PRO2017-10.
• Spreadsheet OIA19-0509 SQU6T final [XLSX, 20 KB]
  • This spreadsheet contains fishing effort data indicating the occurrence of fishing effort for bottom trawls targeting southern arrow squid (SQUBT) for the fishing years 2013/14 to 2017/18. The data has been provided as 0.05 degree grids and a description of the top left co-ordinates for each grid is also included.

Note: The fishing effort and grid information is the same format as displayed for figure A3-3 of AEBR 224 ‘Spatial Assessment of Fisheries Risk for New Zealand sea lions at the Auckland Islands.’ This data has been extracted and formatted by Fisheries New Zealand, and as such may not match exactly with the data analyses and grooming that may occur as part of the PRO2017-10 project. Also AEBR 224 did not include 2017/18 fishing data.

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