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175 posts in Publications

Old growth fishes become scarce under fishing

New research shows that the oldest fish can decline dramatically in fished populations, even when fisheries are sustainable. Old fish declined in 97% of populations when compared to an unfished state, and in about a third of populations, old fish declined by more than 90%. These changes reduce the diversity of fished populations, which can lead to lower stability. Reducing the impact of fishing on old fish would require marine reserves, rotational harvesting, or slot limits that prohibit fishing on all but a narrow range of fish ages. 

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Infectious diseases decline with urbanization and wealth, but not biodiversity

Infectious diseases reduce human health both through death and disability, with the total disease burden being lower in wealthy and more urban countries, but higher in countries with more biodiversity. Contrary to expectations, increases in biodiversity over time did not result in better human health, and in fact higher disease burdens resulted when forest cover increased over time. Thus the key reason why infectious disease burdens have declined in recent decades is a shift towards urbanization and greater wealth, immediately suggesting levers for improving global human health. 

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Fishing portfolios and shifts buffer Alaskan communities from abrupt change

New research on Alaskan fishing communities shows the crucial importance of fishing portfolios and turnover. In 1989, when there were both major ocean and market regime shifts, most communities lost fishing revenue. But those with the greatest diversity of fished species, and those that were most able to switch from one group of species to another, had little lost revenue, or even experienced increased revenue. 

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When do multiple factors act together to endanger animal populations?

Animal populations are endangered when they face multiple human-caused pressures at the same time, especially if those pressures interact to worsen depletion. A new study shows that whether pressures interact to worsen overall pressure, or interact to reduce overall pressure, depends on how animal populations behave at low versus high densities. If the number of offspring that survive for each adult drops off slowly as populations increase, this can unexpectedly lead to trouble, since it is more likely that individual pressures will interact to make things worse. 

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New advice on how to better estimate maximum sustainable yield for fisheries

A major component of fisheries management is using highly complex computer models to figure out the highest catch that can be taken from a fish population—the so-called Maximum Sustainable Yield, or MSY. A critical assumption underlying MSY estimates is how to model the relation between total amount of spawning fish and the resulting offspring that they produce. A new paper by SAFS director André Punt and NOAA researcher Jason Cope examines a wide range of these models to find the best three-parameter version that can independently estimate both the amount of spawning fish and the fishing harvest rate that will produce MSY, concluding that the Ricker-Power model is the best. 

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The power of entire DNA sequences to secure the future of seafood

A new review of the contribution of genomics to seafood management reveals how new questions may be addressed by genetics. Genomics involves sequencing the complete DNA of organisms, which has a great variety of applications, including greatly enhancing our ability to define management units, tracing whether seafood is being labelled correctly when sold, identifying how often salmon stray from their streams of origin, detecting seafood diseases, and measuring the extent of fisheries-induced evolution. 

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Estuaries function better with natural patterns of water flow and suspended organic matter

A new study looks at clams and mussels in five estuaries in Puget Sound, and finds that alterations to river flow, landscape connectivity among adjacent habitat types, or the type and supply of suspended organic matter (detritus), can disrupt food webs at the scale of entire landscapes. Clams and mussels, which cannot move to track food sources, are particularly affected by climate variability, levee systems, water diversion from estuaries, and dwindling availability of detritus due to loss of tidal marsh wetlands. 

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Fisheries can alter the timing of spawning and migration in fish

Fishing can substantially alter when fish migrate and when they breed, says a new review in Fish and Fisheries by SAFS student Michael Tillotson and faculty member Thomas Quinn. For example, fishing closures may increase fishing on late breeders, resulting in a greater proportion of early breeders in the population. Such changes can exacerbate the effects of climate-driven changes in the timing of migration and breeding. 

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