DO TECHNICAL MITIGATION MEASURES MAKE SENSE IN M A N A G IN G A
FISHERY?
Depestele Joche n 1, Piet G e rja n 2, Robinson Leonie3, Polet H ans1 and M a g d a Vincx4
1 Instituut v o o r L an db ou w en V isse rijO n d e rzo e k (ILVO)
A n kerstraa t 1, 8 4 0 0 O o ste n d e Belgium
E -m ail: in fo @ ilv o .v la a n d e re n .b e
2 W a g e n in g e n IMARES
H a rin g k a d e 1, 1 9 7 6 CP, IJm uiden, the N etherlands
3 U niversity o f L iverpool, School o f B io lo g ic a l Sciences, M a rin e and Freshwater B io lo g y
Research G ro u p , BioSciences B u ild in g , C ro w n Street, L ive rp o ol, M erseyside, L69 7ZB, U nited
K in gd om
4 U niversiteit G e n t, V a k g ro e p B io lo g ie , A fd e lin g M a rie n e B io lo g ie
K.L. Ledeganckstraat 3 5 , 9 0 0 0 G e n t, Belgium
Fisheries m a n agem ent is urged to im p le m e n t effective measures fo r the conservation o f
ecosystem structure and fu n ctio n in g . To tha t end a wide range o f potential measures
exist such as T A C /Q u o ta , effort m a n agem ent (including M a rin e Protected Areas, MPAs)
and technical measures, and it is likely tha t none o f these measures will provide the
solution in isolation. For exam ple: fo r the protection o f highly m o b ile species and
species that are not h abitat-specific, such as cod (G adus morhua), MPAs m ight not be
the most suitable measure. Therefore, know ledge and m an ag e m e nt o f the type and
level o f fisheries m a nagem ent that can be used to sustain these species is crucial.
The sustainability o f different levels o f fishing e ffo rt has been w idely investigated and
policies are put in place fo r b alancing the fishing potential with its capacity. However,
fishing gears can have very different catch efficiencies and catches per unit o f effort fo r
different species, especially in mixed fisheries. This notion has triggered fishing g e a r
tech n olog y research to seek technical m o d ifications tha t change the interaction o f
species o r taxa and the fishing gear. The im plications o f technical m itig a tion measures
are m apped carefully at the level o f the in d ivid ua l fishing o p e ra tio n , e.g. at the level o f
a fishing trip. However, the im plications fo r the fisheries and th e ir im p a ct on the
ecosystem are not.
A conceptual fra m e w o rk fo r the assessment o f technical m itig a tion measures (TMMs) is
presented. In a first step the short-term , direct m ortality o f a p a rticu la r fishing g e a r is
estim ated fo r the most im pacted ecosystem com ponents. In the second step, the
developm ent and analysis o f TM M s are reviewed and indicate the changes in species
m ortality. The third step w ill upscale the results to the level o f the fishery and the
ecosystem. In the final step the results are used to estimate the effects o f the proposed
TM M s at the ecosystem level. A retrospective assessment is perform ed as w ell, to ensure
that the effectiveness o f TM M s is not underm ined by any unforeseen a d d itio n a l adverse
effects.
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