Fishing about and about fishing

                               

Opinion on the prevailing scientific basis of fisheries management. as presented by: M. Ben-Yami on the 2009 World Fisheries Day Workshop, on November 20-2, 2009, at Lorient, France. 

 

Quite a few times I encountered situations where fishermen were haggling with management over the quotas or days-at sea allocated to them. In most such cases I found it wrong way to go. They should have questioned, as we’re doing here now, how sound is the science on which the management’s decisions are based. In my opinion, one of the main reasons why the industry is rarely doing this is the weakness of its representatives when faced with scientific terminology and mathematical-statistical formulas. On one hand, fishing people don’t comply voluntarily with rules based on science that seems to them untrue or unreliable. On the other hand, they may not have the scientific knowledge, terminology, and mental tools to argue with scientists and managers and with their mathematical-statistical argumentation. Thus, the way how fishermen present their views and opinions is dismissed as “self-interested”, “anecdotal”, etc.

 

I think, therefore that instead of wrangling over TACs, fishermen should have the underlying science reviewed and verified by scientists independent of the management and official-science system.

 

The fact that the CFP fisheries management is flawed is widely accepted. One of its root problems is that it has been based on inadequate science that largely ignores ecology, including predation, environmental changes and fluctuations, various data-related problems, and the influence on stocks of pollution and habitat destruction.

 

It started in the 1960s, when population dynamics and mathematical models, mainly for single-species stock assessment, later supported by acoustic surveys have become a comfortable option of doing fishery research.

 

Already in 1998 Jim O’Malley wrote that in the process, “mathematics has been elevated to a status which suppresses knowledge and actually detracts from our efforts to acquire knowledge. It supports an intellectual bureaucracy, and has become an excuse to defer investigation into broader questions some of which cannot be enumerated. Although mathematics can help us refine and expand understanding and perhaps even make projections with it. And occasionally mathematics may help us understand something that we did not understand before. But what has happened is that with the ascent of computers, it displaced much of other science”. 

 

The prevailing approach assumes that to find the amount of fish in a stock you take those left from last year, add those recruited this year, subtract those captured - (fishing mortality, F) and those that died from predation and other causes (natural mortality, M). 

 

Science based on such models assumes that only the fishing mortality (F) is significantly changing. It made fishing the almost sole cause for stock size fluctuations. and developed a concept that we can manage a fishery by just controlling the fishing. 

 

An arbitrary value of M = 0.18 to 0.20 picked up some 100 years ago by a German scientist is since followed by sheer inertia. It has been used in the stock-assessment models and I saw it still used by ICES for stock assessment in the Eastern Atlantic and in some cases with attempts to justify it statistically-mathematically by analyzing catch samples comprising several year classes. 

 

This level of M, however, in incompatible with experts estimates that the world's marine birds consume 70M mt of food, versus the 80M mt of global fish landings.  With the predation by marine mammals, fishermen’s catch is perhaps only one third to one half of total mortality, which may make M=~0.5 - 0.66 and far away from the 0.2 figure.

 

Most models isolate single-species fish stocks from other species and ecosystem. This has lead to attempts to manage by more than one single-species, each to their maximum - an ecological absurd. Most of the models hardly comprise the various man-caused non-fishing variables, such as pollution or damage to inshore and offshore fish habitats, and their true-time effects on recruitment, mortality, and vulnerability of fish populations to fishing. Models ignore also climatic/hydrographic fluctuations and anomalies, although species with narrow temperature preference limits, especially during spawning, hatching and larval stages may be critically affected.

 

Survival of larvae and juveniles depends also on having the right food, at the right place and time. Want of food causes area shifts and/or starvation. Lean, hungry fish is usually not overfishing. Few fish that are fat often is.

 

Knowledge and consideration of fish biology, physiology, ecology, behaviour, and environment can carry the management to protect fish at the right time and place, and prove more rational and effective than quantitative stock assessments.

 

Fisheries data are often unreliable for several reasons:

1. Fishermen find themselves in a sort of Catch-22 situation: when they truly report large catches - their reporting is often leading to quota or effort cuts; when they under-report – the results are similar.

2. Research and survey vessels follow track routine, which fish don’t. Thus, fish accumulations may be often missed.  The same goes for hydro-acoustic surveys, which apart from their inherent inexactness, cannot be everywhere at the same time. There’s plenty of evidence that fish are normally found at an optimal temperature for their species; this suggests that the fish are migrating to stay within their preferred temperature ranges. Fish may swim upwards to midwater or move to larger depths to find cooler waters; but not official surveys – they stick to their routine.

3. Research-survey vessels use "standard" outdated gear, not adjusted to behaviour and fish location changes, so that their often meagre catches may misrepresent the actual state of the stock.

 

The prevailing fishery science ignores the complex relations between stock size, cannibalism, and food availability, and hence the fact that large spawning stocks often produce poor recruitment and vice-versa: small stocks may produce large year classes.

 

In short, models, combining speculated approximated, guesstimated, and otherwise make-believe values, with some mathematical-statistical cosmetic make-up, are unable to produce precise figures. Notwithstanding, many current management systems, based on TACs and quotas, exert demands on their scientists for precise figures that the science is unable to and thus shouldn't satisfy. The integrity of scientists who know better, but comply to please the bosses is questionable, to say the least.

 

RECOMMENDATION: INDEPENDENT REVIEW OF THE MANAGEMENT’S  SCIENCE:

This inadequate science survives so long, for the "peer reviewing" of its presumptions and recommendations is done by scientists from the same discipline and school of thought. Scientists critical of the whole methodology, are not asked to review stock assessments. Independent scientists, dissident from the state controlled systems are ignored, silenced, left unemployed, not given research grants, etc.

 

 RECOMMENDATION: Combine science with fishermen’s experience and observations:

 

Computer models, neither simple nor those involving multiple, including environmental, parameters can do without involving sea-going experience, research and experimentation, and real time information from fishermen. 

 

The people who are on the ocean every day know that when one thing happens, another is sure to follow. Or maybe not… - they know that too. This knowledge is stored in their experience, their logbooks, and their memories. They know it from their fathers and from themselves. They know what a cold winter or an active hurricane season may mean for the next year’s fishing. They know that the abundance of one species is a good reason to expect the abundance or scarcity of another. They sense cause and effect when statistical data is unable to find “significance”. All too often, that knowledge is dismissed as “anecdotal,” and not of use in management.

 

RECOMMENDATION: Ask fishermen… Scientific results should be reviewed also by experienced fishermen to see if they make sense and if they can agree with their current and past observations.