Unlike the Sea Change 2017 marine spatial plan that sought to phase out bottom impact fishing from the Hauraki Gulf Marine Park the governments response (Revitalising the Gulf 2021) was to create ‘trawl corridors’. Bottom trawlers do not have a public license to keep smashing the seafloor, a 2021 Horizon Research poll had 84% support for a banning the practice. I love the seafloor and volunteer for an organisation that restores damage done to it by bottom impact fishing. I’m completely opposed to trawling as a fishing method but I put my hand up to help limit its impact in the Gulf using a science based process by joining the Hauraki Gulf – Benthic Spatial Planning Advisory Group (HG-BSPAG).

This was my first experience in a collaborative decision making process run by the Government with industry representatives. I represented an environmental Non-Government Organisation (eNGO), there were three eNGO participants, everyone else was either from NIWA, central & local govt or the fishing industry. The process was chaired and controlled by Fisheries NZ. The other two eNGO participants were awesome and I learnt a lot from them.

I particularly liked the data first approach to marine spatial planning, Zonation is a great tool and I liked the way it starts by removing the human impacts then making an economic case for re-introducing them. Unfortunately some data that would have been useful was not quite complete.

Fisheries NZ controlled the outputs by defining what is in scope. Here is a list of requests that were disregarded:

1. Ground truthing the modelling work (out of scope).
2. Modelling the distribution of Unwanted Organisms (UOs) . We know from NIWA surveys that trawl nets catch UOs in the HGMP, transporting UOs is an offence under Section 52 of the Biosecurity Act 1993. By excluding UO’s from the study FNZ failed to protect native benthic habitats from UO’s which can be spread by bottom impact fishing (see appendix for more details).
3. Infauna (animals that live in the sediments) that are sensitive to bottom impact fishing were excluded from the modelling due to technicalities.
4. Mobile species that contribute biogenic habitat like tipa / scallops (see appendix) and burrowing animals like ghost shrimp and crabs were excluded because they were mobile which did not suit their definition of biogenic habitat. This is ridiculous as the smallest grid size is 250m and previously mentioned adult animals are unlikely to move more than 10m.
5. Important habitats for fish (like spawning and nursery areas) were not considered (out of scope).
6. The indirect effects of bottom impact fishing. Sediment plumes from bottom impact fishing choke and kill filter feeding animals and smother photosynthesising plants. These effects were not included but have been discussed at the end of the report.
7. Climate change impacts (e.g. CO2 released from resuspending sediments and heart urchins moving deeper as water warms) also not included but have been discussed at the end of the report.
8. Modelling the economic benefits of excluding bottom impact fishing to other fisheries that don’t impact the seafloor, this could have dramatically altered the findings (out of scope).
9. Monitoring changes in the money made in an area over time during the transition from one fishing method to another, I think it’s critical this is done with any changes to bottom impact fishing.
10. Using the regulations, not existing fishing effort, as the starting point for limiting Danish seining (see appendix on Danish seining regulations). Despite multiple requests FNZ would not even put the existing regulations on the maps.
11. Protecting the deeper areas of the HGMP (see appendix).

We did not discuss substrate. Is it better to trawl on sand which emits a smaller plume but may transition to mud with intensified disturbance, or mud which has a larger sediment plume? We know repeated bottom impact fishing alters the chemistry of the seafloor.

The narrow scope of the project was frustrating because there is an aspiration for Ecosystem Based Management of the Hauraki Gulf Marine Park. Once all the environmental effects of bottom trawling and Danish seining are considered, the fishing methods should be banned everywhere.

I have some sympathy for fisheries managers, they have specific deliverables and get pushed around by industry. I did think their approach was often callous, in the face of uncertainty they often chose the status quo rather than taking a more precautionary approach. One member of the Hauraki Gulf Fisheries Management Plan Working Group HG-FMPWG that will finish the corridor design work has publicly criticised the process.

There were no opportunities for feedback on the corridors the scenarios produced. Final trawl corridor design will be Fisheries NZ’s responsibility and will get input from the HG-FMPWG. Other than the above I have no criticisms of the process, it just needs bigger budgets and managers who care more about te taio. I learnt a lot and am happy to volunteer my time again to use scientific modelling in a spatial planning process to protect the environment.

One difficulty I had was proposing trawl corridors. I decided not to volunteer a low impact scenario because the process had already generated a near zero impact scenario which I thought was reasonable (Similar to Figure 14C in the published report – 90% of recovery potential habitat and current trawl footprint & current/proposed protected areas and 100% of current distribution of biogenic habitat (minimising impacts on trawl fishery.) This meant I was left very unhappy with the scale of the proposed scenarios. It was obvious that the scenarios would need work before Fisheries NZ could designate corridors, however I may end up regretting that decision.

I hope Fisheries NZ will monitor recovery (which may take centuries) the data gained could help ground truth this model and develop more robust models in future.

You can read the published report on the design process here: Exploring the use of spatial decision support tools to identify trawl corridors in the Hauraki Gulf Marine Park

Advice for the Hauraki Gulf Fisheries Management Plan Working Group

The outputs of the process will be used by the Hauraki Gulf Fisheries Management Plan Working Group to design bottom trawling corridors in the marine park. Here are some key points they should be aware of:

• Because the process is not ground truthed and does not account for secondary impacts, important habitats for fish or climate change impacts a precautionary approach should be taken. (I suggested massive buffers but they were deemed out of scope).
• Danish seining impacts have not been included in the model. This skews the impacts, recovery in areas where this fishing method is practiced has been understated.
• The corridors should be much deeper (further from the coast) to avoid the illegal transport of Unwanted Organisms.
• Consider the existing Danish regulations as the starting point, not the area where the fishing method is currently practiced.
• Protect the deeper areas of the Gulf because they are included in the Hauraki Gulf Marine Park (see appendix).
• Include monitoring (fisheries method transition) in any recommendations.
• Take special note of the sediment resuspension impacts detailed on page 68 of the report which were excluded from the study.

Appendix

Avoiding tipa / scallop beds

Running heavy trawl gear over tipa / scallop beds is incredibly damaging and foolish behaviour. It not only damages the tipa including juveniles, but also the settlement substrates the tipa use as part of their lifecycle. The Review of Sustainability Measures for New Zealand scallops (SCA 1 & SCA CS) for 2022/23. 3.1.18 states that:

“Within the Hauraki Gulf Marine Park, overlap between trawl activity and scallop beds will be considered as part of the proposal to establish defined ‘trawl corridors’ that will limit the areas where bottom trawling can continue to operate. With the introduction of electronic reporting and Global Position Reporting (GPR) on commercial fishing vessels, Fisheries New Zealand has the ability, through fine scale data, to monitor any notable overlap between fisheries and methods.”

It was frustrating that even though tipa are the most surveyed biogenic habitat in the Gulf the fisheries scientists decided that instead of identifying them they would just model their associated habitats. In the paper they literally say they ‘hope’ that this would mean the beds would be avoided rather than just mapping them out. Only the small beds that remained open at the time of the study (the fishery has since collapsed with bottom impact fishing implicated as a key stressor) were removed from the study area.

The rationale for the exclusion of tipa was that they are very mobile. This is ridiculous given the grid size of the study is 250m. Adult tipa and burrowing animals are unlikely to move more than 10m in their lifetime. For adult tipa mobility see Morrison, M. A. (1999). Population dynamics of the scallop Pecten novaezelandiae in the Hauraki Gulf (Doctoral dissertation, ResearchSpace@ Auckland).

Danish seining regulations

The restrictions prescribed in fisheries regulations for Danish seining define a different area than what is currently applied by Fisheries NZ. The State of our Gulf 2020 quotes Fisheries  NZ as ‘committed to reviewing this discrepancy as part of management actions put forward in a fisheries plan for the Hauraki Gulf’. The discrepancy is not recorded in the final report.

Protecting the deeper areas of the HGMP

The deeper areas of the HGMP were excluded from the final scenarios. I asked that they be protected because:

1. The edges of continental shelves are biodiversity hots spots. Predicted diversity along the depth incline is one of the reasons for excluding the area from the model.
2. This process was designed to protect biodiversity.
3. This is the only deep water area in a marine park in New Zealand.

Unwanted organisms discussion document

Here is the discussion document on an unwanted organism (Mediteranean fanworm) I prepared for the working group, similar logic could have been applied to other species including the two recently introduced Caulerpa species.

Omissions

The report details protection measures proposed by Sea Change 2017 but omits the most important benthic protection measure, “the phase out of all bottom trawling, Danish seining and scallop dredging from the Hauraki Gulf, with all such methods excluded by 2025” It’s a strange omission that reads like an attempt to exclude the measure from the history books.

Submission on the Natural and Built Environment Bill and Spatial Planning Bill

Submission on sustainability measures for scallop (SCA CS) for 2023/24

Fisheries New Zealand (FNZ) is designing an NZ first Fisheries Management Plan for the Hauraki Gulf Marine Park that they are calling Ecosystem Based as part of the Revitalising the Gulf – Government Action on the Sea Change Plan. They are seeking an advisory group as part of their discourse of delay (Revitalising the Gulf was launched six months ago). I have not asked to be part of the process. Because the advisory group does not have any decision making capability it won’t be very effective in managing commercial fisheries (like Sea Change), this is because FNZ has been captured by industry (Parker 2016). FNZ also only want advice from people with experience in Fisheries Management, based on the state of Gulf this is like asking the Tabacco Industry to regulate smoking. But they might be able to reduce recreational catch which I think has the biggest impact on the Gulfs reef ecosystems. Unfortunately of the five voices, only one will be from the environmental sector, so it doesn’t have much of a chance of being ecosystem based, and to be truly ecosystem based; the scope would have to include the management of other impacts on the ocean like plastics and sediment (Government departments have hand picked recommendations from the Sea Change which was the only attempt at an integrated management plan). The plan will start to address the effects of fishing which FNZ should have been doing since the act was established in 1996. The Sustainable Seas Challenge has a project investigating what Ecosystem Based Fisheries Management would look like for the Gulf, it’s so political even the scientific proposal is two months late.

The outcomes of the proposed plan are:

• Healthy, functioning aquatic environments that support sustainable fisheries
• Fish stocks at levels which meet the needs of treaty partners and stakeholders
• Inclusive and integrated regional participation in governance of fisheries

Like more than 10% of New Zealanders I don’t eat our native wildlife, my suggestion for creating a really Ecosystem Based Fisheries Management Plan would stop all fishing in the Gulf and not be very popular 😀 So here are some ideas that might be a bit more palatable. First of all my outcomes would be different:

• Clearer water
• Restored kelp forests (no kina barrens & carbon sequestration)
• Increased biodiversity and intact ecosystems
• Increased abundance
• Climate change resilience

Obviously we need to stop bottom contact fishing (as per Sea Change and the Hauraki Gulf Forum goals) but on top of that, this is what I would do to achieve the above outcomes.

Provision 1: No more killing of functionally extinct native wildlife and habitats.

These species need to recover to much higher levels to perform ecosystem services and increase biodiversity. Species I consider functionally extinct. Kutai / Green-lipped mussels, Kōura / Spiny rock lobster and Packhorse rock lobster, Hapuku, Sharks etc.. Where populations of species are not known fishing should stop (precautionary approach) and the group complaining about the closure should pay for the science to measure it (user pays). Many species are in such a bad state we now need to also stop fishing practices that might kill them as bycatch (eg. Killing juvenile Hapuku who have a pelagic phase in Purse Sein nets). The sooner we stop killing the species the sooner we will see them recover. The advisory group will suggest long rebuild times for populations so they can keep killing as much as they can for as long as possible. I would stop all killing right now and wait until stocks have recovered to 80% biomass and there contribution to ecosystem function has been measured before considering harvesting again.

Provision 2: Reductions in the take of food for functionally extinct native wildlife.

This has been said before but just for marine mammals “Management of the Greater Hauraki Gulf should take into account the potential for trophic and system-level effects of re-establishment/recovery of marine mammals towards historical levels.” MacDiarmid 2016. I think it should apply to other functionally extinct predators like Hapuku.

Provision 3: No more killing native filter feeding animals that live on the seafloor.

Not everybody will love this idea but everyone will love the result – clearer water. The Gulf has been overloaded by sediment and nutrients and the tap is still running. Filter feeding animals help clear the water by removing sediment from water while looking for food (mostly phytoplankton).

Increasing populations of filter feeders that live on the seafloor, Kutai / Green-lipped mussel, Tipa / Scallop, Tuangi / Cockle, Hururoa / Horse mussel, Tio / Oyster etc will increase water clarity which will increase kelp biomass and carbon sequestration. Other benefits include more complex benthic habitats which are nurseries for fish, removal of harmful pathogens and even the production of sand. Increased water clarity benefits visual predators like Tāmure / Snapper and Human spearfishers.

In some parts of the Gulf a lot of money is being spent trying to actively restore shellfish, by not killing shellfish in areas where we still have remnant populations we can increase larval supply across the Gulf. Passive and active restoration activities are complementary.

Provision 4: Dramatic increases in forage fish populations.

By weight most of the fish in the Gulf are also filter feeders. These forage fish swim around in large schools with their mouths open feeding on zooplankton. Unlike the bivalves listed above they do not bind sediment up in balls and deposit it on the seafloor. This means not all the above benefits of increasing their populations apply, however its likely they play a critical role in the Gulfs ability to sequester carbon. I’m most interested in increasing forage fish populations because they are critical to many Gulf food webs. Commercial harvest of some forage fish like Blue mackerel has increased 300% in the last 20 years. This is reducing the amount of food available to protected species that we want more of, like whales and seabirds. Populations of most forage fish are not known so that would be the first step, I would then set the Total Allowable Catch (TAC) for Ecosystem Based Management (EBM) very low (E.g. 20% unfished biomass) and invest more in monitoring the breeding success of their predators (seabirds and cetaceans) and adjust the TAC accordingly.

Provision 5. Maximum size limits for recreational species.

Restoring Kōura / Spiny rock lobster and Packhorse rock lobster numbers is going to take a long time and they will need help to push back Kina / Sea urchin barrens and regrow our kelp forests. We can fix this by creating a maximum size limit for Tāmure / Snapper. Bigger snapper are better at managing Kina populations and are dramatically better at making baby Tāmure / Snapper. If the later is true for all finfish then it makes sense to introduce the maximum size limit across all species. Recreational fishers could still have fishing competitions but they would have to be catch-and-release. Large fish should learn to avoid hooks overtime reducing harm and selecting for traits that support catch-and-release. R&D would be required to match the gear to fish size for the longline fisheries but as I said earlier this group hasn’t been set up to have the power to influence commercial take.

Provision 6. Effort controls with gear limits.

We need to get much less good at killing fish. Methods like nets, pots and dredges need to be banned along with long lining. Gear restrictions should also apply to methods with high levels of bycatch. This is not just what is used (eg. set nets catching protected bird species) but also how (eg. Let’s stop all fishing in workups and spawning aggregations). This means a lot of re-educating fishers, the introduction of a license would be sensible (like Australia which has had licenses for 20 years and is not known for being progressive on wildlife protection).

Provision 7. A network of Marine Protected Areas covering at least 30% of the Gulf.

Source–sink dynamics are not hard for anyone interested in population management to understand. No-harm areas where populations can reach near 100% of their un-fished state can feed exploited areas. No one would design a conservation management plan on land without a wildlife refuge. I don’t see why the design of network of such areas should not be part of an ecosystem based population management plan in the ocean.

“It would be logical to close some scallop beds and create passive restoration (broodstock areas) to increase the fishery yield” 

– Dr Mark Morrison, Shellfish Restoration Co-ordination Group, December 2021.

A recent poll showed that the 30% protection policy had 77% support from the public including Māori. These areas would serve as a reference point to compare the impacts of fishing elsewhere in the Gulf and provide the best possible resilience to climate change impacts like ocean acidification (which scares me more & more every time I look into it). One of the most difficult hurdles for Marine Reserve applications is the perpetual nature of the policy. Creating MPAs under a fisheries management plan would be a lot easier, voices of those seeking protection in the Gulf (like me) will go quiet the longer the areas stay closed to fishing and visa versa.

It’s a good time to share ideas on what an Ecosystem Based Fisheries Management plan would look like. There are some attempts to define it here, but they all try to avoid the idea of simply killing less native wildlife, no one wants to pay for that research.

References

MacDiarmid 2016. Taking Stock – the changes to New Zealand marine ecosystems since first human settlement: synthesis of major findings, and policy and management implications. New Zealand Aquatic Environment and Biodiversity Report No. 170 A.B. MacDiarmid et al. June 2016. Ministry for Primary Industries.

Parker 2016. Hon David Parker https://www.parliament.nz/en/pb/hansard-debates/ rhr/document/HansS_20160920_054787000/parker- david

UPDATE 6 MAY 2022

The Hauraki Gulf Fisheries Plan Advisory Group has been announced. The Chair is an old school fisheries scientist who is responsible for the current fish populations. There are three commercial voices and one (or one and a half) recreational. There are only two voices for serious change. I am not counting on it delivering significant change.

UPDATE 3 MAR 2023

My submission on the proposed plan which refines thoughts I began in this blog post. It includes additional critique of the draft plan and many new measures.