New England Cod Collapse and the Climate

Abstract

To improve fishery management, there is an increasing need to understand the long-term consequences of natural and anthropogenic climate variability for ecological systems. New England’s iconic cod populations have been in decline for several decades and have recently reached unprecedented lows. We find that 17% of the overall decline in Gulf of Maine cod biomass since 1980 can be attributed to positive phases of the North Atlantic Oscillation (NAO). This is a consequence of three results: i) a 1-unit increase in the NAO winter index is associated with a 17% decrease in the spring biomass of age-1 cod the following year; ii) this NAO-driven decrease persists as the affected cohort matures; iii) fishing practices appear to exacerbate NAO’s direct biological effect such that, since 1913, a 1-unit increase in the NAO index lowers subsequent cod catch for up to 19 years. The Georges Bank cod stock displays similar patterns. Because we statistically detect a delay between the NAO and subsequent declines in adult biomass, our findings imply that observed current NAO conditions can be used in stock forecasts, providing lead time for adaptive policy. More broadly, our approach can inform forecasting efforts for other fish populations strongly affected by natural and anthropogenic climatic variation.

Projecting shifts in thermal habitat for 686 species on the North American continental shelf

“…Long-term shifts in species distributions have been linked to directional shifts in their preferred temperatures [ 3 , 4 ], as the geographic distributions of marine species are strongly linked to temperature tolerance [ 1 ]. Further, regional species productivity [ 5 , 6 ] and phenology [ 7 , 8 ] can be highly sensitive to variation in water temperatures, which may be a driver of long-term shifts [ 9 ]. The implications of geographic shifts of marine species have already been observed in global fisheries catches and changes in catch composition from regional landings data are consistent with poleward shifts in species distributions [ 10 ].…”

Use of state‐space modelling to identify ecological covariates associated with trends in pinniped demography

“…The NAO index is a general reflection of ecosystem state rather than a local index, but it has been shown to be related to variation in the biomass or quality of various fish species that contribute to harbour seal diets (Arnotts & Ruxton, 2002;Dippner, 1997;Meng, Oremus, & Gaines, 2016;Stige, Ottersen, Brander, Chan, & Stenseth, 2006). The NAO index is a general reflection of ecosystem state rather than a local index, but it has been shown to be related to variation in the biomass or quality of various fish species that contribute to harbour seal diets (Arnotts & Ruxton, 2002;Dippner, 1997;Meng, Oremus, & Gaines, 2016;Stige, Ottersen, Brander, Chan, & Stenseth, 2006).…”

“…The significant relationship with the winter NAO index may well also be influencing the seals' demography through a change in prey availability. The NAO index is a general reflection of ecosystem state rather than a local index, but it has been shown to be related to variation in the biomass or quality of various fish species that contribute to harbour seal diets (Arnotts & Ruxton, 2002;Dippner, 1997;Meng, Oremus, & Gaines, 2016;Stige, Ottersen, Brander, Chan, & Stenseth, 2006). Because harbour seals are generalists, adapting their feeding behaviour and diet to their local habitat (Reder, Lydersen, Arnold, & Kovacs, 2003;Sharples et al, 2012), they may show a response to years that reflect low availability of multiple prey species.…”

Snapshot of an On-Going Trade in Reptile Wholesaler, Kebumen, Central Java: Preparation, Trading, and Conservation Implications

“…This particular estimation can be observed in the destruction of Cod fish (Gadus morhua) which is exploited due to its large population and considered to be sufficient to continually be exploited. The exploitation causes a domino effect which affects the economic and social aspects [20]. Further effect for drastic population reduction would affect the wholesaler more than the poacher itself [2].…”