New England Cod Collapse and the Climate.

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

The small world of global marine fisheries: the cross-boundary consequences of larval dispersal

Fish stocks are managed within national boundaries and by regional organizations, but the interdependence of stocks between these jurisdictions, especially as a result of larval dispersal, remains poorly explored. We examined the international connectivity of 747 commercially fished taxonomic groups by building a global network of fish larval dispersal. We found that the world’s fisheries are highly interconnected, forming a small-world network, emphasizing the need for international cooperation. We quantify each country’s dependence on its neighbors in terms of landed value, food security, and jobs. We estimate that more than $10 billion in annual catch from 2005 to 2014 is attributable to these international flows of larvae. The economic risks associated with these dependencies is greatest in the tropics

New England Cod Collapse and the Climate.

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

Data from: New England cod collapse and the climate

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

Geolocated fish spawning habitats

Abstract Fish spawning locations are a crucial input into fisheries management and conservation plans, and many stocks are especially sensitive to the environmental conditions within these localized zones. Globally collated data on spawning locations across many species has been unavailable, hindering global stock assessments and analyses of sustainable development and global environmental change. To address this, we created a geocoded fish spawning dataset using qualitative spawning information from FishBase and Science and Conservation of Fish Aggregations (SCRFA). We cleaned and geocoded the spawning locations of 1,045 marine fish species into 2,931 regions. Each spawning region is defined by one or more polygons, and most spawning regions are associated with spawning months. The resulting dataset covers oceans globally. This dataset will be useful to scientists studying marine fish population dynamics and their interactions with the physical environment on regional to large scales

Meng_Oremus_Gaines_replication

This zip file contains all code and data to replicate results in Meng, Oremus, Gaines, PLOS ONE, 201

Effects of current and past NAO on cod catch.

<p>Panels <b>(A)</b> and <b>(B)</b> show regression coefficients from a multiple regression model of commercial cod catch on current and past NAO variability for the Gulf of Maine and Georges Bank stocks, respectively. The x-axis represents the number of years prior that a 1-year increase in NAO occurred. 90% confidence interval shown. Panels <b>(C)</b> and <b>(D)</b> show observed log catch (black line), predicted log catch using only secular time trends (orange line), and predicted log catch using both secular time trends and observed NAO (green line). Panel <b>(E)</b> shows observed NAO variation.</p

Birth-year NAO effect on cod biomass.

<p>Panels <b>(A)</b> and <b>(B)</b> show regression coefficients representing the effect of a 1-unit increase in birth-year NAO on a cod cohort as it matures from age 1 to 6 for the Gulf of Maine and Georges Bank stocks, respectively. Each coefficient comes from a separate multiple regression model (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158487#pone.0158487.e001" target="_blank">Eq 1</a>). 90% confidence interval shown. Panels <b>(C)</b> and <b>(D)</b> show observed surveyed log adult biomass (ages 2–6) (black line), predicted log adult biomass using only secular time trends (orange line), and predicted log adult biomass using both secular time trends and observed NAO (green line). Decomposition follows Eqs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158487#pone.0158487.e003" target="_blank">2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158487#pone.0158487.e008" target="_blank">3</a>. Panel <b>(E)</b> shows observed NAO variation.</p

Winter NAO and Sea Surface Temperature (SST) correlation.

<p>The map shows the grid-cell-level correlation between winter (DJFM) NAO and SST from 1982 to 2013 with a quadratic time trend removed (see SI). Purple contour lines indicate areas where correlation p-value<0.1. Dashed boxes indicate the statistical area for the Gulf of Maine and Georges Bank stocks. Grid resolution is 0.25 degrees latitude x 0.25 degrees longitude. Correlation values in bar at right of map.</p