Fish that learn migration from their elders are more susceptible to fishing

Many fish species repeatedly migrate from feeding areas to spawning areas, and their migration pathways could be innate or learned. Two possible models are examined for learning of these migration pathways: the Diffusion Model holds that fish head to spawning site near where they themselves hatched; while the Go With the Old Fish Model involves young fish joining schools of older fish, and learning migration pathways from the older fish. In a new paper, the implications of these two models are examined. Following older fish results in much great variability in fish numbers from one place to another, and when fish numbers decline, this strategy results in some spawning sites being abandoned while other spawning sites have much higher fish numbers. In addition, the Go With the Old Fish Model results in lower sustainable catches and a less productive fishery overall. Such patterns mimic observed herring population changes, highlighting the importance of research that identifies how fish learn migration pathways. The new paper by Alec MacCall of the Farallon Institute for Advanced Ecosystem Research, and his coauthors, which include SAFS postdoc Margaret Siple, SAFS director André Punt, and Tessa Francis, who is a Research Scientist at the Puget Sound Institute/UW Tacoma and Managing Director of the Ocean Modeling Forum, was published in the ICES Journal of Marine Science.

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