A Spatially Distinct History of the Development of California Groundfish Fisheries

Abstract

During the past century, commercial fisheries have expanded from small vessels fishing in shallow, coastal habitats to a broad suite of vessels and gears that fish virtually every marine habitat on the globe. Understanding how fisheries have developed in space and time is critical for interpreting and managing the response of ecosystems to the effects of fishing, however time series of spatially explicit data are typically rare. Recently, the 1933–1968 portion of the commercial catch dataset from the California Department of Fish and Wildlife was recovered and digitized, completing the full historical series for both commercial and recreational datasets from 1933–2010. These unique datasets include landing estimates at a coarse 10 by 10 minute “grid-block” spatial resolution and extends the entire length of coastal California up to 180 kilometers from shore. In this study, we focus on the catch history of groundfish which were mapped for each grid-block using the year at 50% cumulative catch and total historical catch per habitat area. We then constructed generalized linear models to quantify the relationship between spatiotemporal trends in groundfish catches, distance from ports, depth, percentage of days with wind speed over 15 knots, SST and ocean productivity. Our results indicate that over the history of these fisheries, catches have taken place in increasingly deeper habitat, at a greater distance from ports, and in increasingly inclement weather conditions. Understanding spatial development of groundfish fisheries and catches in California are critical for improving population models and for evaluating whether implicit stock assessment model assumptions of relative homogeneity of fisheries removals over time and space are reasonable. This newly reconstructed catch dataset and analysis provides a comprehensive appreciation for the development of groundfish fisheries with respect to commonly assumed trends of global fisheries patterns that are typically constrained by a lack of long-term spatial datasets.

Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem

“…We found that trophic hotspots are important fishing areas for coastal pelagic and groundfish fisheries, although in the case of fisheries for coastal pelagic species in particular, the proximity to major ports may be another contributing factor regarding the spatial distribution of catches (Miller et al. ). While it is difficult to determine the full impacts of fishing on higher trophic level species that may compete with fisheries for prey, as well as the cumulative impacts on marine ecosystems more generally, one important first step is evaluating the spatial overlap between fisheries and key ecosystem components.…”

“…Miller et al. () provide further details and methods on the estimation of historical (1930–2000) fishery extraction patterns off California. For the purposes of this study, we summarized the total extracted metric tons (per km 2 of the appropriate habitat) of fish of each taxonomic group to the CalCOFI grid, and examined their relationship with the trophic hotpot index (biological PC).…”

Comparing Apples to Oranges: Common Trends and Thresholds in Anthropogenic and Environmental Pressures across Multiple Marine Ecosystems

“…Each ecosystem in this study has, at some stage in the last half century, experienced overfishing (Bakkala et al, 1979;Rosenberg et al, 2007;Walters et al, 2008;Link et al, 2011a;Miller et al, 2014). The impacts of overfishing are complex, but well researched.…”

Reproductive dynamics of Pacific sanddab, Citharichthys sordidus, off the central coast of California

“…While the cause and magnitude of the decrease in length at maturity remains unknown, it is nevertheless an important consideration when comparing reproductive potential between historic and current catches and examining potential cumulative impacts of fishing on the ecosystem as a whole. As trawl fisheries in California were first initiated in the late 1800s, targeting Pacific sanddab and other shallow-water flatfish in the waters off of San Francisco (Miller et al, 2014;Scofield, 1948), even an early effort to characterize growth and reproduction (Arora, 1951) may have potentially evaluated an altered population. Regardless of the actual drivers of this shift, the results of this analysis, in concert with their characteristic broad distribution and significance to the food web, suggest that this species may represent a model organism for both monitoring and gaining a better understanding of the cumulative consequences of both fishing and climate-driven shifts in productivity and life-history characteristics through the California Current ecosystem over the next 50 years, and potentially beyond.…”