Improving selectivity of the Baltic cod pelagic trawl fishery: Experiments to assess the next step

2010 ◽  
Vol 103 (1-3) ◽  
pp. 40-47 ◽  
Author(s):  
Niels Madsen ◽  
Vesa Tschernij ◽  
Renè Holst
Keyword(s):  
Trawl Fishery ◽  
The Baltic ◽  
Baltic Cod

scholarly journals Factors affecting rule compliance with mesh size regulations in the Baltic cod trawl fishery

2007 ◽  
Vol 64 (8) ◽  
pp. 1603-1606 ◽  
Author(s):  
Petri Suuronen ◽  
Vesa Tschernij ◽  
Pekka Jounela ◽  
Daniel Valentinsson ◽  
P-O. Larsson
Keyword(s):  
Gadus Morhua ◽  
Management Practice ◽  
Mesh Size ◽  
Factors Affecting ◽  
Trawl Fishery ◽  
Management Measures ◽  
Gradual Introduction ◽  
Minimum Landing Size ◽  
The Baltic ◽  
Baltic Cod

Abstract Suuronen, P., Tschernij, V., Jounela, P., Valentinsson, D., and Larsson, P-O. 2007. Factors affecting rule compiance with mesh size regulations in the Baltic cod trawl fishery. – ICES Journal of Marine Science, 64: 1603–1606. In this study, we evaluate the efficiency and applicability of a series of gear-based management measures, enforced since 1990, whose purpose was to improve size selectivity in the trawl fishery for Baltic cod (Gadus morhua). In general, our study revealed that these measures had no marked effect on the capture and discard of young cod. Legal and illegal manipulation of selective codends was widespread. The adoption of a codend design that offered a modest increase in selectivity, but had a good match with the legislated minimum landing size (MLS), led to greater compliance, demonstrating that a mismatch between MLS and selectivity should be avoided. It was also obvious that, generally, the fishing industry did not tolerate large short-term losses. Our evaluation is that overly ambitious rules will be circumvented, and frequent and incoherent changes in the regulations represent bad management practice. A gradual introduction of restrictions and participation by fishers in the decision-making process will increase compliance.

Escape windows to improve the size selectivity in the Baltic cod trawl fishery

2002 ◽  
Vol 57 (3) ◽  
pp. 223-235 ◽  
Author(s):  
Niels Madsen ◽  
René Holst ◽  
Leslie Foldager
Keyword(s):  
Size Selectivity ◽  
Trawl Fishery ◽  
The Baltic ◽  
Baltic Cod

scholarly journals The Baltic Cod Trawl Fishery: The Perfect Fishery for a Successful Implementation of the Landing Obligation?

2018 ◽  
pp. 197-218 ◽  
Author(s):  
Daniel Valentinsson ◽  
Katja Ringdahl ◽  
Marie Storr-Paulsen ◽  
Niels Madsen
Keyword(s):  
Successful Implementation ◽  
Trawl Fishery ◽  
The Baltic ◽  
Baltic Cod

Improving species and size selectivity in the Baltic cod trawl fishery with two simple codend designs

2021 ◽  
Vol 236 ◽  
pp. 105846
Author(s):  
Niels Madsen ◽  
Ólafur A. Ingólfsson ◽  
Hans Nilsson ◽  
Petri Suuronen
Keyword(s):  
Size Selectivity ◽  
Trawl Fishery ◽  
The Baltic ◽  
Baltic Cod

scholarly journals Deoxygenation impacts on Baltic Sea cod: Dramatic declines in ecosystem services of an iconic keystone predator

AMBIO ◽  
2021 ◽  
Author(s):  
Alessandro Orio ◽  
Yvette Heimbrand ◽  
Karin Limburg
Keyword(s):  
Ecosystem Services ◽  
Baltic Sea ◽  
Gadus Morhua ◽  
Generalized Additive Model ◽  
Additive Model ◽  
Maximum Length ◽  
The Baltic Sea ◽  
Hypoxic Zone ◽  
The Baltic ◽  
Baltic Cod

AbstractThe intensified expansion of the Baltic Sea’s hypoxic zone has been proposed as one reason for the current poor status of cod (Gadus morhua) in the Baltic Sea, with repercussions throughout the food web and on ecosystem services. We examined the links between increased hypoxic areas and the decline in maximum length of Baltic cod, a demographic proxy for services generation. We analysed the effect of different predictors on maximum length of Baltic cod during 1978–2014 using a generalized additive model. The extent of minimally suitable areas for cod (oxygen concentration ≥ 1 ml l−1) is the most important predictor of decreased cod maximum length. We also show, with simulations, the potential for Baltic cod to increase its maximum length if hypoxic areal extent is reduced to levels comparable to the beginning of the 1990s. We discuss our findings in relation to ecosystem services affected by the decrease of cod maximum length.

scholarly journals Eastern Baltic cod recruitment revisited—dynamics and impacting factors

2016 ◽  
Vol 74 (1) ◽  
pp. 3-19 ◽  
Author(s):  
Friedrich W. Köster ◽  
Bastian Huwer ◽  
Hans-Harald Hinrichsen ◽  
Viola Neumann ◽  
Andrei Makarchouk ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Large Scale ◽  
Prey Availability ◽  
Stock Assessment ◽  
Future Research ◽  
First Feeding ◽  
Spawning Areas ◽  
The Baltic ◽  
Eastern Baltic ◽  
Baltic Cod

The Eastern Baltic cod abundance started rapidly to increase in the mid-2000s as evidenced by analytical stock assessments, due to increased recruitment and declining fishing mortality. Since 2014, the analytical stock assessment is not available, leaving the present stock status unclear and casting doubts about the magnitude of the recent increase in recruitment. Earlier studies identified main factors impacting on cod reproductive success to be related to the loss of two out of three spawning areas in the 1980s caused by lack of major Baltic inflows with a concurrent reduction in salinity and oxygen. Other important factors include prey availability for first-feeding larvae, egg predation by sprat and herring and cannibalism on juveniles, all in one way or the other related to the prevailing hydrographic conditions. These factors cannot explain increased reproductive success in the last decade, as the period was characterized by an absence of large-scale Baltic inflows since 2003 and persistent anoxic conditions in the bottom water of the deep Baltic basins. This questions the perception of the increased recruitment in later years and challenges our present understanding of cod recruitment dynamics in the Baltic Sea. In this contribution, we review evidence from the recent literature supplemented by information from latest research cruises to elucidate whether cod reproductive success indeed has increased during the last decade, and we suggest the key processes responsible for the recent dynamics in cod recruitment and outline directions for future research.

scholarly journals Understanding the release efficiency of Atlantic cod (Gadus morhua) from trawls with a square mesh panel: effects of panel area, panel position, and stimulation of escape response

2014 ◽  
Vol 72 (2) ◽  
pp. 686-696 ◽  
Author(s):  
Bent Herrmann ◽  
Harald Wienbeck ◽  
Junita Diana Karlsen ◽  
Daniel Stepputtis ◽  
Erdmann Dahm ◽  
...  
Keyword(s):  
Escape Response ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Mesh Size ◽  
Accumulation Zone ◽  
Trawl Fishery ◽  
Trawl Fishing ◽  
Panel Effects ◽  
The Baltic ◽  
Stimulation Of

Abstract Based on size selectivity data for more than 25 000 cod (Gadus morhua) collected during experimental trawl fishing with six different codends, all of which included a square mesh panel, we investigated the effect on cod-release efficiency based on the size of the square mesh panel area, position of the square mesh panel, and stimulation of the escape response. Based on the results, we were able to explain why the BACOMA codend, applied in the Baltic Sea cod directed trawl fishery, releases juvenile cod efficiently, whereas other designs, including a square mesh panel with similar mesh size, are less efficient. Our main findings reveal that the release efficiency of the square mesh panel in the BACOMA codend depends largely on the overlap of the square mesh panel and the catch-accumulation zone in the codend, where cod do not have the option of just drifting further back in the trawl when proximate to the panel. On the contrary, the reduction in panel size by 50% did not significantly affect the release efficiency when the panel overlapped with the catch-accumulation zone. It was possible to stimulate an escape response for cod to achieve a release through a square mesh panel positioned away from the catch-accumulation zone. Our findings demonstrated that this release was as efficient as for a panel mounted in the catch-accumulation zone of the codend. Devices that stimulate behaviour may improve the release efficiency of cod through square mesh panels in other fisheries where this is a problem.

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