Menakhem Ben-Yami looks into the issue of fisheries management.
It appears that fisheries management science and fisheries science move on straight, parallel, never meeting courses.The former is employed by governmental or inter-governmental fishery management systems, and is based on population dynamics of selected commercial fish rather than on their ecology. The latter science comprises fish life history, ecology, fishery-system oceanography, ocean food pyramid and inter-special dynamics.
Tunnel vision
Management-scientists' tunnel vision focused on overfishing, apparently disregard writings by those researchers who study whole fishery ecosystems. Some years ago,a Canadian professor, George Rose, told a NW Atlantic cod-fishery symposium that stocks cannot be “recovered” by diagnosing overfishing, catch restriction and moratoria, as there are also other factors responsible. Dr Chris Reid said that an oceanic “regime shift” had affected the abundance and timing of the cod larvae's planktonic food. Fish move northwards at the same rate as plankton. Dr M J Kaiser proposed adjusting fishing operations to the life history of cod.
“Recent reports suggest that declines in stock abundance are caused by difficult to separate combined results of fishing and unfavorable environment,” said Dr Brian Rothschild, professor emeritus at the University of Massachusetts, more recently. “Assessments need to be phrased in this context.” he added. “Development of such an approach is a major scientific effort that should start now.”
According to Professor Ray Hilborn of the University of Washington: "… there's general acceptance now that fish productivity is a result of both climate and fishing." And he warned that, although by following climatic regime shifts, we can harvest a higher percentage of the stock during good regimes than during bad ones…"what seems a safe level of fishing in good times can be disastrous when times are bad.”
According to Dr Steve Cadrin, President of the American Institute of Fishery Research Biologists (AIFRB) and University of Massachusetts' professor of Fisheries and Oceanography, the scientific basis for the 2013 (Canada-USA.) Transboundary Resources Assessment Committee's assessment is insufficient. He recommended limiting catch advice until a new assessment of yellowtail stock is complete.
Dr Tim Adams, a Pacific fishery scientist and manager has been saying for a couple of decades now that "there are a lot more things affecting fish stocks than just fisheries" and that "the impact on coastal fisheries from contamination is greater than the commercial and recreational catches combined." But the effects of pollution seem to be studiously circumvented in publications. For example, J C Jones and J D Reynolds wrote in Reviews in Fish Biology and Fisheries 7(4) that of a total of 19,199 studies in Aquatic Sciences and Fisheries Abstracts and other sources, published during 20 years, only 19 (!!) linked pollution to fish reproduction.
Russian scientists, L B Klyashtorin and A A Lyubushin, in a book Cyclic Climate Changes and Fish Productivity, published in English a couple of years ago by the VNIRO (All-Russian Scientific Institute for Fisheries and Oceanography), show that historical multi-annual and multi-decadal variations in fish yields are associated with planetary, climatic and oceanic 60-80-years fluctuations.
Temperature cycle
Also, a British study led by Professor Martin Edwards, has confirmed 60-80-year cycle between warm and cold sea surface temperatures in the North Atlantic, called Atlantic Multidecadal Oscillation (AMO). The boundary in the English Channel between warm-water sardines, and cold-preferring herring, shifts northwards in warm periods, and retreats southwards in cool periods. The AMO's effects on herring sardine and other fish are dramatic. During the 1930-1960 warm period, the weight of herring spawning in Norwegian seas increased by a factor of 10, while the herring fishery in the English Channel collapsed and was replaced a few years later by sardines. At the same time, the cod fishery extended northwards along the coast of Greenland. During the cool 1970s, the herring population in the Norwegian Sea fell from 16 million tons to just 50,000, but since the start of the next warming period in the 1990s it has recovered to 1960 levels.
“A profound warming event occurred on the Northeast Shelf this spring, impacting throughout the ecosystem,” said Dr Kevin Friedland, of NOAA’s Northeast Fisheries Science Center (NEFSC). The record average sea surface temperature in the region was over F51 degrees - three degrees higher than that over the past three decades. The report emphasised that even more extreme variations were documented in two of the ecosystem’s great feeder estuaries - Chesapeake and Delaware bays, where temperatures were more than six degrees above historical averages on the surface and more than five degrees above average at the bottom. Simultaneously, tumultuous changes occurred in the location and concentration of the great Northern Shelf biota. Scientists tend to avoid generalising cause and effect, but there is broad consensus that the warmer waters are pushing many species - including cod - off their traditional grounds.
"Temperature is a major factor shaping the distribution of marine species given its influence on biological processes," said Dr Jon Hare, lead author of a study published in the journal PLOS ONE and director of the NEFSC’s Narragansett Laboratory. "Many fish species are expected to shift in result of climate change, but we don’t fully understand the mechanics of how temperature interacts with a species life history, especially differences between juvenile and adult stages." Ray Beverton, one of the fathers of fish-population models, said in 1992 that more fish is eaten by other fish, sea-mammals, and birds than it is by man. "Regulation by catch limits is fundamentally flawed, except the simplest of single species fisheries,” he said.
As I'm reading these and also former FAO's Dr Gary Sharp, Dr Serge Garcia, Dr John Caddy and other investigators, it appears as if fisheries management scientists keep using scientifically-inadequate models fed with inadequate data that hardly, if at all cover factors other than fishing, and are unable to follow environment-induced trends and fluctuations. They simply ignore all this, because their employers require quantitative stock assessments, the precision of which borders on fallacy. More often than not, their science is neither "best available" nor adequate.
I'm offering 700 words of my monthly page to any management scientist who openly and in simple language wishes to refute the above and justify their approach. Well…?
If you are a scientist who would like the opportunity to justify your approach to fisheries management, please contact Menakhem Ben-Yami at benyami@actcom.net.il
