Fish scientists cast doubt on costly warming calls
“Seventy years of warming may be followed by cooling as it used to be before. …we should pay more attention to the relative influence of management steps and climatic variations on fish stocks,” said Dr. Svein Sundby of the Bergen Institute of Marine Research, speaking on the long-term effects of climate change on fish populations and their forage organisms in the NE Atlantic.
“The collapse in the 1950s-1960s of the Norwegian herring stock was a combination of cooling and overfishing” Sundby told experts in fishery economics, management, marine biology, oceanography and climate at the two-day event on trans-disciplinary thinking on the influence of past and future climate shifts on fisheries. The workshop, June 20-21, called by GLOBEC, was entitled “Economic Effects of Climate Change on Fisheries”.
Models and data from Ragnar Arnason of the University of Iceland, Torbjorn Lorentzen of the Bergen Centre of Fishery Economics and Prof. William E. Schrank Memorial University of Newfoundland all indicated a correlation between warm periods and good northern fishing. Arnason predicted improvement in Icelandic landings, and Lorentzen said that both Norwegian herring and mackerel would react positively. “With such optimistic forecasts – Arnason asked – does it make sense to take expensive measures to reduce global warming?”
In the Barents Sea fisheries, “biological and economic impacts of relatively small changes in management regimes may be more pronounced than the physical, biological and economic changes caused by global warming,” Dr. Arne Eide of the University of Tromsø, told the meeting.
“The abundance of California sardine is related to environmental fluctuations therefore ecosystem-based management should monitor longer range physical and biological changes in the system,” Jerrold Norton of the Pacific Grove, California, Southwest Fisheries Science Center said.
There was criticism at the workshop of intellectual exercises in mathematical modelling of possible future scenarios because they contained high levels of uncertainty and little data. Hence their relevance to real life fisheries seemed only incidental.
Prof. Rognvaldur Hannesson of the Bergen Centre for Fisheries Economics, who also chaired the meeting, examined different scenarios and found that, if temperature change forced stocks from one country’s EEZ to another’s, then shared migrating stocks might be overfished by the competing countries during such an “exodus”.
Thorir Sigurdson of the University of Akureyri in Iceland ascribed the departure of Atlanto-Scandian herring to warmer waters, and its effect on the Icelandic economy, to an incursion of the cold East-Icelandic current. “Maybe this summer herring [has] started coming back” said Sigurdson. Kathleen Miller of the U.S. Center for Atmospheric Research said that international management of highly migratory stocks, such as tropical tuna, should involve flexible responses to climate variability.
Prof. J.R. McGoodwin of the University of Colorado, Friday Nyaja of the Malawian Fisheries Department and Menakhem Ben-Yami of Israel described how climatic shifts and the resulting changes in fishery resources actually affected fishing people and their communities.
McGoodwin has for years studied people in high-latitude regions. In Alaska, the commercial sector is less resilient to conditions change than subsistence communities. Even with poor salmon runs, in the summer the Yup’ik Inuit catch the little they need for the whole year. Still, radical and major decadal changes may cause unpredicted consequences.
“In Iceland – said McGoodwin – the cycling boom-and-bust capelin fishery interacts on fishmeal markets with the El Nino/La Nina effects on the Peruvian anchovy fishery. A wrong combination of the above hurts Icelandic fishermen limited by their capelin-quotas. It’s the other way around when El Nino depresses the anchoveta fishery and capelin stock is up.
McGoodwin’s report implied criticism of the Icelandic quota system, as affecting social cohesion, favouring large-scale operations and frustrating small-scale fishermen. He suggested it dampened their flexibility to shift to other species and fisheries for which they own no quotas, and their sensitivity to fish reactions to weather and climate-forcing.
Njaya explained how the fisheries of Lake Chilwa, Malawi, are affected (including occasional collapses) by repeated climate-forced water-level variations and their ecological consequences. “In such environments climatic variations’ impact is much more important and radical than fishing effort,” he said. When a fishery collapses there was a total loss of income for 3,000 boat-and-gear owners, 7,000 crews, 3,700 traders and the workers and suppliers associated with the He backed up his conclusions with financial evaluations of losses caused by climatic phenomena.
Ben-Yami reported how, some 50 years ago, a minor climatic shift brought about a spell of poor fishing years and this triggered a privatisation process in Israel’s trawling sector and caused social dislocation among co-operatives and collective villages.
