Review: Global Marine Primary Production Constrains Fisheries Catches (DOI: 10.1111/j.1461-0248.2010.01443.x)

Andrew Long

Marine Ecology and Conservation

September 15, 2011

Review: Global Marine Primary Production Constrains Fisheries Catches

The second portion of this article is essentially the discussion of the implications of these findings and more or less the short comings of the researchers’ methods. Essentially this study seeks a correlation or relationship between gross primary production, as measured by satellite quantification of chlorophyll a in surface waters of fishery zones, and fisheries production. It’s a bottom up control analysis of pelagic ecosystems which examines the effects of primary production in terms of net production at the fisheries level.

Conceptually this is a rather kinetic approach to gross production based on the idea of feed conversion ratios and makes a number of assumptions about the structure of trophic webs, fishing pressure, as well as the size, life span, and fecundity of the populations in a given region. Loss of primary production equals less secondary, tertiary, and quaternary production and so on. The researchers normalize spatial productivity in terms of fisheries population based on reported landings, where some areas are more consistently productive than others. Any fisherman will tell you this isn’t a particularly surprising finding. More substantially, a relationship between primary production and landings was indicated by normalizing spatial norms. The verdict is net decrease, which also isn’t surprising. The researchers relegate the decrease in primary production primarily to ocean warming effectively changing spatial productivity. Eventually they conclude that although surface temperatures likely play a key role in influencing the spatial concentration of primary producers, it is the spatial (and quantitative) element of their distribution that is most troubling for fisheries and net production.

Even though researchers showed a strong relationship between these two parameters, the question remains; is this the primary factor contributing to decreased landings? Or has consistent and more precise fishing effort primarily to blame for the decrease? Several studies have found a net decrease in primary production in conjunction with decreased landings in a number of other regional studies. Chassot, et. al. recognized the importance of demonstrating this as a global phenomenon. Taken regionally, one could reason that a net decrease in production is the result of the migratory nature of fish and/or primary producers. Traditionally, this is the mindset. Humbly, at the edge of the sound, men ponder their effects on the seemingly infinite ocean and cannot ascertain their actions could possibly be significant. Arrogantly we ignore the signs.

Another fact this work points to inadvertently, is the effects of primary consumers. The history of Georges Banks groundfish comes to mind. Landings increased consistently off New England until the mid 1900’s, leading up to an enormous collapse of the groundfish population that affected the region for over 20 years, and in many ways still does today. During the end of that period, landings were steadily increasing, but many people fail to realize is that total catch was comprised of many different species. As hake, haddock, and cod landings decreased, gross total landings increased supplanted by of demand for fishmeal from sardines, menhaden, pilchard, and herring, which are used to make agricultural feeds. The collapse and reduction of many of these grazers/primary consumers has major implications and probably accounted for the lasting effects of the groundfish collapse.

Not included in this article, is the interesting and related science of enhancing primary production by utilizing ferrous sulfate. There’s little question that it enhances primary production several fold. However, the initial idea was to sequester carbon dioxide into the phytoplankton and lower global CO2 concentration. It is unknown what proportion of the sequestered carbon dioxide is deposited in the deep ocean via this method as quantification has proven to be elusive. Might this be just the stone we need to kill the two proverbial birds?

Overall, it’s difficult not to come to the realization that global fisheries are essentially facing a “double whammy" of bottom up consequences (as explained here) in the face of top down effects from fishing effort. The paper underscores the increasing pressure fisheries are facing and how fishing at, or over, maximum sustainable yield leaves no margin for error. For example consider how deeply these factors would compound a viral or seasonal suppression of recruitment/survival.

-Chassot, Emmanuel. "Global marine primary production constrains fisheries catches." Ecology Letters 10 (2010): 495-505. ICON. Web. 13 Sept. 2011.

-Molyneaux, Paul. Swimming in Circles: Aquaculture and the End of Wild Oceans. New York: Thunder’s        Mouth Press, 2007.

-Woods Hole Oceanographic Institution. Oceanus Vol 46 no.1 (2008): Print.

Article review by Andrew Long

Article review by Andrew Long

Article: “Buyers offer reality check on pursuit of sustainable seafood.”

Author: Bob Tkacz

Source: Aquaculture North America Jan/Feb 2011.

            In his report “Buyers offer reality check on pursuit of sustainable seafood,” following the 2010 Chinese Seafood Sustainability Summit, Bob Tkacz highlights some of the lectures and discussions at this year’s international forum for seafood farmers, buyers, traders, and retailers. The author suggests that the increasingly popular buzzword “sustainability,” is somewhat ambiguous for consumers and retailers alike. He illustrates this point well by contrasting the strategies implemented by two of North America’s largest seafood processors/retailers.

            The development of Eco-labels, proliferated by environmental NGO’s, holds some intrinsic values of their own. Although it means different things in different markets, an unspecified market survey cited in the article shows that 80% of customers want more information on sustainability issues, and 90% of consumers were willing to switch to sustainably caught products. According to David Smith, president of Sobey’s Seafood, customers are savvier and the state of sustainably caught seafood is going from “nice-to-do” to “need-to-do.” Many feel that NGO certifications aren’t coming fast enough and good retailers know they must do their own homework to buy from fisheries that are at least on a trajectory towards sustainable catch.

            Strategies for marketing to their clientele differs among retailers, some rely on eco-labels and consumer perception of sustainable practices, while others have deeper roots in the market. Sobey’s retail chain throughout Canada reports that they don’t rely on eco-labeling because they have a 100 year tradition in the industry, but they support sustainable practices to maintain their image among consumers. Corporations like Santa Monica Seafood however, cater to sophisticated clientele throughout southern California where eco-labels and sustainably caught products are key to image and sales. Despite their heavy reliance on eco-labels as part of their reputation, Santa Monica Seafood, as well as Sobey’s, maintains that if a product is legal they have to offer it in order to maintain relationships with suppliers and business among unscrupulous buyers such as individuals, restaurants, and the other retailers they supply.

            The article cites industry projections by the Global Aquaculture Alliance, estimating unprecedented growth over the course of the next 10 years, largely due to the increased demand for seafood, which will make expansion of aquacultural operations feasible for many new species and regions. Tenured retailers know that such demand will also put pressure on traditional fisheries, and warn others not to paint themselves into a corner by pledging to eliminate non-certified products from their markets by specific dates.