the plotki magazine (pdf) - Moving Baltic Sea

S T O R I E S F R O M T H E S E A S I D E →and GPS to ensure that the recreational fishermen havea good catch. Curiously, these sports-fishermen arefacing no restrictions, such as individual catch limits in contrast to the professional fishermen whose catchis strictly regulated by EU quotas. And even if the codfishing isn’t what it used to be, Zimmermann gives assurancesthat the recreational fishermen on his vesseldo catch their cod. More cod than the remaining professionals,he adds with a sly smile.So, where then does all the cod on the Warnemündemenus come from, in an out of season month like July,with just a few fishermen left? Zimmermann gives assurancesthat the Warnemünde fishermen are not theones that deliver to the resort’s eateries; maybe hereand there they sell a couple of fish but that’s it. Theoverwhelming mass of Warnemünde’s fish comes fromaround ten Rostock based fish delivery companies. Oneof those grand distributors is F&F Fisch und FeinkostGmbH. F&F reports that the company delivers about60,000 kilograms of fish annually to Warnemünde, toabout 50 different restaurants, takeaways and hotels.Their cod is not solely of Baltic origin. They buy from thebig freezer trawlers that fish in the North Sea and theBarents Sea.3 ―If one wants to learn more about the situation of thecod in the Baltic (and, by implication, about the impacthumankind can have on the eco-system sea), onceagain a Mr Zimmermann is a good contact. ChristopherZimmermann is deputy director of the Institute of BalticSea Fisheries (OSF) in Rostock; an expert scholar oncod and herring, Zimmermann is probably more talkativethan all the Warnemünde fishermen together. Hiswelcoming and friendly way pleasantly contrasts withthe rather reserved manner of his namesake and theother Warnemünde fishermen (who somehow neverseemed to lose their slight suspicion of the strangerfrom Berlin).“In the Baltic Sea we have very special conditions”,explains Zimmermann. “This is why the cod stocks haveto be managed very carefully, if we want to ensure a sustainableharvest.”And, as if sensing that all the bad news on over-fishingand the depletion of the world’s fish stocks may makesuch a claim sound outrageous, he repeats, “Yes, we canharvest cod in a sustainable manner.”This is exactly the purpose of the OSF to study thepreconditions for sustainable fishing management inthe Baltic. The institute resides in a modern four-storysteel skeleton construction in Rostock’s Fischereihafen,about five kilometres up the Warnow from the oldstream. The location couldn’t be more suitable. Fromthe windows one enjoys a splendid view of the river and of the nearby cold storages of F&F and Venfisk, anotherone of Rostock’s fish delivery companies.The special conditions of the Baltic, Zimmermanngoes to explain, are the key to understanding the situationof the cod living there. Unlike in the North Sea,for instance, where commercial fishing is almost solelyresponsible for the poor state of the cod, the influenceof fishing on the Baltic cod populations can be saidto be maybe fifty percent. The other half can be attributedto environmental factors, which presently arenegatively influenced by human activity other thancommercial fishing.The most crucial adaptation of Baltic fish, is its abilityto cope with the Baltic’s low salinity. However, explainsZimmermann, to ensure successful reproduction,a minimum level of salinity is required. Cod do spawn inopen water but if salinity in the spawning areas dropsbelow a certain point, their eggs lose the ability to freefloat,they suck in water, sink to the bottom and explode.This is why the Baltic cod has chosen a few deep basins(such as the Gotland and the Bornholm deeps) of theotherwise shallow sea, as its spawning grounds. In thosedeep basins the salinity is the highest. Since salt wateris heavier than fresh water, the saline inflows from theNorth Sea are trapped there.These exact spawning grounds are threatened bya massive intake of nutrients. Fertilizer used in agricultureis washed to the Baltic via the rivers. The result is oxygendepletion, a process also observed and well knownin freshwater systems. If phytoplankton dies, it sinks tothe ground where it is decomposed by bacteria a processin which dissolved oxygen is reduced. In the deepbasins of the Baltic, oxygen-depletion has led to the lossof potentially successful spawning areas for the cod andthe eggs suffocate. According to Zimmermann, in someplaces cod find only one meter, within an 84 meter watercolumn, in which the conditions (oxygen level andsalinity) allow for egg survival.6