Technology for a better society AFS 2014, Quebec 1 Bent Herrmann, Ludvig A. Krag (DTU Aqua), Manu Sistiaga FishSelect a New Method for Predicting Size Selectivity of Fishing Gears

Technology for a better society Development of the selective properties of fishing gears towards desired species or multispecies specific size selectively is a widely used approach to achieve sustainable fisheries. Traditionally, the estimation and optimization of the size selective properties of fishing gears have been carried out following a kind of trial and error procedure based solely on sea trials. However, conducting sea trials is expensive and time consuming, which makes this optimization difficult solely based on such an approach. 2 Background

Technology for a better society FishSelect has in recent years supplemented the purely experimental- based selectivity assessment methods. 3 Role of FishSelect ? FishSelect provide guidelines and predictions of selectivity that reduce the amount of trials necessary to develop a suitable gear design for a given fishery. FishSelect can help interpreting results obtained from experimental fishing, leading to a deeper and more comprehensive understanding of size selectivity in fishing gears. Can a fish of this species and size escape through a mesh with this size and shape?

Technology for a better society Fish morphology and mesh geometry play an important role for size selectivity in fishing gear. Thus, the FishSelect methodology is based on a combination of laboratory experiments and computer simulations which involves assessment of the fish morphology relevant for size selectivity. Three main steps in the methodology: I.Experiments in laboratory a)Morphology measurements b)Fall-through trials II.Simulation of laboratory experiments III.Prediction of selective properties for different mesh shapes/fishing gears by simulation 4 FishSelect Methodology The methodology is outlined in Herrmann et al. (2009) which also demonstrate the application to study size selection of Cod (Gadus morhua):

Technology for a better society 5 Experiments in laboratory - morphology Cod in MorphoMeterScanningEdge detection Aggregating data Regression analysis Cross section contours are extracted and measured for each fish using the MorphoMeter, scanning and image analysis. Length to cross section size is established based on fitting parametric models for the cross sections. Parametric fitting

Technology for a better society 6 Experiments in laboratory – fall-through From 8000 to fall-through trials per species ( fish x mesh templates)

Technology for a better society Simulation of fall-through experiments The fall-through experiments are simulated assuming different levels and type of cross-section compression. The compression modelled leading to best agreement was used for predictions. CS1CS2 CS1 measured CS1 penetration model CS1 CS2 Measured Compressed 7

Technology for a better society 8 Prediction of selective properties A new series of simulations is conducted using a virtual population of fish based on the established morphological relations to predict the selective properties for different nettings. Design Guide (DG)

Technology for a better society 9 FishSelect Studies The flexibility in FishSelect has enabled investigating many different species. The method has been applied in several international collaborations. Parametric descriptions of fish shapes. FishSelect includes more than 100 different shape models. CS1CS2 CS1 CS3CS2

Technology for a better society 10 Understanding the size selectivity of redfish (Sebastes spp.). Published in Journal of Northwest Atlantic Fishery Science (ISSN: ), vol: 44, pages: Herrmann et al. (2012): Understanding the size selectivity of redfish (Sebastes spp.). Studied effect of codend mesh size on size selection. Could explain experimental results from fishing by FishSelect.

Technology for a better society 11 Understanding sorting grid and codend size selectivity of Greenland halibut (Reinhardtius hippoglossoides). Codend size selection: effect of mesh size Grid size selection: effect of bar space Could by FishSelect understand and predict size selection of Greenland Halibute both in diamond mesh codends and in grid-based systems.

Technology for a better society 12 A simulation-based attempt to quantify the morphological component of size selectivity of Nephrops norvegicus in trawl codends. Square mesh Codend size selection Diamond mesh Codend size selection Could by FishSelect simulate the size selection of Nephrophs in codends by considering different modes of contact with the meshes.

Technology for a better society 13 Other Fishselect studies. Other FishSelect studies have been conducted. For some are results already published: Sistiaga, M., Herrmann, B., Nielsen, K. N., Larsen, R. B., Understanding limits to cod and haddock separation using size selectivity in a multispecies trawl fishery: an application of FISHSELECT. Can. J. Fish. Aquat. Sci 68: 927–940. Krag, L., Herrmann, B., Madsen, N., Frandsen, R., Size selection of haddock (Melanogrammus aeglefinus) in square mesh codends: A study based on assessment of decisive morphology for mesh penetration. Fisheries Research 110: Herrmann, B., Sistiaga, M., Larsen, R. B., Nielsen, K. N., Size selectivity of redfish (Sebastes spp.) in the Northeast Atlantic using grid-based selection systems for trawls. Aquatic Living Resources 26: Krag, L.A., Herrmann, B., Iversen, S., Engås, A., Nordrum, S., Krafft, B.A., Size selection of Antarctic krill (Euphausia superba) in trawls. In Plos ONE. while other studies are in progress and include the following species: Lemon Sole (Microstomus kitt); Plaice (Pleuronectes platessa); Flounder (Platichthys flesus); Red mullet (Mullus barbatus); Hake(Merluccius merluccius); Common Pandora(Pagellus erythrinus); Brown Shrimps (Crangon crangon).

Technology for a better society 14 Conclusion - End FishSelect can: Produce design guides for towed gears for different fisheries. Assist with interpretation of experimental results obtained from sea trials. Provide a better foundation for exploring new design ideas for selective gears to be tested at sea. Provide basis for a quick and well-founded advice about technical regulations in different fisheries. Thanks for your Time!