Thinking about shifting baselines and fisheries

herring fishing

 

Historic Herring Fishery – Photo Vancouver Sun

People have short memories, and it turns out so do our fisheries management institutions. With each passing generation people grow accustomed to lower and lower abundance of commercially and culturally important fish, resulting in what Daniel Pauly calls shifting baseline syndrome. From Atlantic Cod, to salmon, steelhead and Pacific Herring, modern management approaches have often been hindered by a failure to grasp the former abundance and spatial distribution of these once abundant species. A paper out recently in the Proceedings of the National Academy of Sciences (PNAS) by a group of researchers based at Simon Fraser University highlights this issue, using archeological evidence from First Nations middens the Salish Sea to Southeast Alaska to track the distribution and abundance of Pacific Herring  through time. They conclude that Herring populations were once more widely distributed, more abundant, and more stable. In recent years Herring populations in the region have exhibited dramatic fluctuations and remain depressed in many areas. This is particularly relevant given a DFO proposal to open Herring fisheries on the Central Coast this year, something which the Heiltsuk are opposing.

Similar considerations exist for anadromous salmonids, and efforts to reconstruct historic abundance using cannery records reveal that modern escapement targets are drastically below historic levels of abundance. I’m particularly interested in the potential for fisheries to induce changes in population spatial strcuture. If external forcings such as climate change or over fishing have altered spatial structure (ie the distribution of fish in available habitat) it could seriously hinder recovery. In the case of salmon I can’t help but wonder how much ongoing anthropogenic climate change is already influencing survival in the ocean. Given the amount of variability in the marine survival data and the relative scarcity of information on marine survival, these changes may already be underway without our knowing.

check out their paper:

http://www.pnas.org/content/early/2014/02/13/1316072111.full.pdf+html

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