Fishing in Freefall

11th April 2013 in Fisheries Science

The International Council for Exploration of the Sea (ICES)’s most recent advice has confirmed that fishing pressure across the main commercial stocks has fallen to a remarkable degree.

Fishing in Freefall

This graph in the ICES advice illustrates vividly how after something like 70 years of incremental increases in fishing mortality (F), the trends after the year 2000 have taken a dramatic dive. This fall in fishing pressure coincides closely with the period during which an array of “cod recovery” measures were applied to EU fleets, although many other factors are undoubtedly involved.

Fishing mortality in the demersal and benthic stocks has been halved since 2000.

The fall in fishing mortality is remarkable in that it applies to all of the three main species groups pelagic (including herring and mackerel), demersal (including cod, haddock and whiting) and benthic (the flatfish including sole and plaice). It also applies right across the whole of the North East Atlantic area, including the North Sea and Baltic and waters around the UK.

Although the development of the pelagic stocks has taken a different course from the benthic and demersal, they are now rapidly catching up.

ICES summarises the situation:

Fishing Mortality for benthic stocks gradually increased over time until about year 2000 and have since reduced substantially. For demersal stocks the increase was steeper in the beginning of the time period, peaked around year 2000 and has reduced since. The pelagic stocks have had a very different development over time. F increased significantly in the late 1960s and early 1970s. This resulted in the well known collapse of several important herring and mackerel stocks. Since then, F has been quite low and stable and like for the other two types of stocks, has decreased since year 2000.In many respects this development will come as no great news to many fishermen who have seen the fishing fleets reduced by decommissioning, consolidation and attrition, to the extent that previously busy fishing grounds are now quite deserted. But it is important to acknowledge the significance of the fact that this trend is now established in scientific opinion and also to consider its implications.

Implications

The clear shift to a lower fishing mortality rate brings with it the need rethink the way we approach both fisheries advice and fisheries management. When the overwhelming concern was to reduce fishing pressure because it was such a dominant factor, there was little need to think too deeply about multi-species interactions – they didn’t really come fully into play. But now that the impact of fishing has been reduced, the need to consider predation patterns and cannibalism becomes much more urgent. ICES' view is that stocks can become so large that they deplete their food sources and eventually eat their own kind. It is necessary therefore to think about the next steps in advice and management: It may be that it will be necessary to increase fishing pressure on some species to achieve an optimum balance. ICES has been working for 30 years on multi-species models. These can now be put to use to inform management decisions.

Another implication lies in the realm of public perceptions. “We all know that fish stocks are collapsing”, has become such an automatic media refrain that it has been difficult for the public to understand that things have changed. But changed they have. North Sea cod, the iconic fish and chips species, is rebuilding steadily to safe biological levels; many stocks are at the management goal of maximum sustainable yield and others are on the way. The recovery of some stocks like North Sea plaice is nothing short of breathtaking, with a biomass beyond anything seen within the historical record.

This is not to say that there aren’t some stocks that have yet to respond in the same way: West of Scotland and Irish Sea Cod are two examples where other factors may be impeding recovery. But the dominant downward trend is too well established, too widespread in geographical terms and across so many diverse fisheries, to be dismissed as a statistical blip.

One telling point in the scientists’s advice puts paid to a number of claims of celebrity chefs and journalists that their own heroic efforts have turned a catastrophic situation around. By the time that Johnny-Come- Latelys such as The End of the Line and Hugh’s Fish Fight turned their attention to fishing the trends discussed above were well established.

Causes

The precise reasons why fishing mortality has dropped so decisively in recent years are not straightforward to discern. Numerous management initiatives have come into play simultaneously and disentangling which worked from which didn’t simply isn’t feasible after the event.

Fleet reductions, tradable quota, increased selectivity, landing controls, effort control, an altered industry mindset, cod avoidance including real time closures have all been in the mix. Some have undoubtedly contributed, others have had perverse effects. ICES points tobetter control, for example in the Baltic Sea. Norway has been able to check the Russians in the Barents Sea. Other candidates include a move towards long term management plans, setting TACs in relation to maximum sustainable yield and better relations between the fishing industry and fisheries scientists. The answer lies surely in some combination of the above but the weight accorded to each is something that science cannot provide.

ICES, however, does not give much credit to the theory that it is nature itself that has created this positive trend in fishing mortality. All species and ecosystems shifting in the same direction simultaneously simply sounds improbable, they conclude.

This article has borrowed freely from both ICES’ 2012 advice and a forthcoming article produced by the Danish Fishermen’s Association. The NFFO acknowledges its debt to both.