GILLNET SELECTIVITY OF LAKE TANA PISCIVOROUS FISH: LABEOBARBUS MEGASTOMA
Keywords:
Bi-modal, Labeobarbus, Lake Tana, Selectivity
Abstract
Gillnet selectivity parameters and its impacts on the population of the Lake Tana Labeobarbus megastoma, were estimated from fishery-independent catches in multi-panel gillnets with stretched mesh sizes ranging from 60 to 140 mm. Selectivity on L. megastoma was assessed using the PASGEAR software. Five different functional models; normal location,normal scale, gamma, log-normal and bi-modal were used to fit the selectivity curves to the catch data. It was shown that the bi-modal function was the best fit to the data. For the bi-modal selectivity curves, the optimum lengths (100% retention probability) for the 60, 80, 100, 120 and 140 mm mesh sizes were 24.18 cm, 32.24 cm, 40.3 cm, 48.36 cm and 56.42 cm, respectively. Considering the size at first maturity (L 50% ), 100 mm mesh size was found to be the most adequate mesh for exploiting the minimum allowable landing size (35 cm).
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References
Baranov, F.I. (1948). Theory of fishing with gillnets. In: Theory and Assessment of Fishing Gear. Pishchepromizdat, Moscow. (Translation from Russian by Ontario Department of Lands and Forests, Maple, Ont.)
Carol, J. and García-Berthou, E. (2007). Gillnet selectivity and its relationship with body shape for eight freshwater fish species. J. Appl. Ichthyol. 23: 654–660.
de Graaf, M., Machiels, M.A.M., Tesfaye Wudneh and Sibbing, F.A. (2003). Length at maturity and gillnet selectivity of Lake Tana‟s Barbus species (Ethiopia): Implications for management and conservation. Aquat. Ecosyst. Health 6 (3): 325–336.
de Graaf, M., Nentwich, E.D., Osse, J.W.M. and Sibbing, F.A. (2005). Lacustrine spawning: Is this a new reproductive strategy among „large‟ African cyprinid fishes? J. Fish Biol. 66:1214–1236.
De Silva, S.S., Schut, J. and Kortmulder, K. (1985). Reproductive biology of six Barbus species indigenous to Sri Lanka. Environ. Biol. Fish. 12: 201–218.
Dinçer, C.A. and Bahar, M. (2008). Multifilament gillnet selectivity for the red mullet (Mullus barbatus) in the Eastern Black Sea Coast of Turkey, Trabzon. Turk. J. Fish. Aquat. Sci. 8: 355–359.
Dos Santos, M.N., Gaspar, M., Monteiro, C.C. and Erzini, K. (2003). Gillnet selectivity for European hake Merluccius merluccius from southern Portugal: Implications for fishery management. Fish. Sci. 69: 873–882.
Erzini, K., Gonçalves, J.M.S., Bentes, L., Lino, P.G., Ribeiro, J. and Stergiou, K.I. (2003). Quantifying the roles of competing static gears: Comparative selectivity of longlines and monofilament gillnets in multi-species fishery of the Algarve (southern Portugal). Sci. Mar. 67: 341–352.
Gunderson, D.R., Callahan, P. and Goiney, B. (1980). Maturation and fecundity of four species of Sebastes. Mar. Fish. Rev. 42:74–79.
Hansson, S. and Rudstam, L.G. (1995). Gillnet catches as an estimate of fish abundance: A comparison between vertical gillnet catches and hydroacoustic abundances of Baltic Sea herring (Clupea harengus) and sprat (Sprattus sprattus). Can. J. Fish.Aquat. Sci. 52: 75–83.
Holden, M.J. and Raitt, D.F.S. (eds.) (1979). Manual of Fisheries Science. Part 2-Methods of Resource Investigation and their Application. FAO Fisheries
Technical Paper No. 115, Rev. 1, Rome, Italy.
Hovgärd, H. (1996). A two-step approach to estimating selectivity and fishing power of research gillnets in Greenland waters. Can. J. Fish. Aquat. Sci. 53: 1007–1013.
Hovgärd, H. and Lassen, H. (2000). Manual on Estimation of Selectivity for Gillnet and Longline Gears in Abundance Surveys. FAO Fisheries Technical Paper. No.397, Rome, Italy.
Kolding, J. (1999). PASGEAR. A Database Package for Experimental or Artisanal Fishery Data from Passive Gears. An introductory manual. University of
Bergen, Department of Fisheries and Marine Biology, Bergen, Norway.
Millar, R.B. (1992). Estimating the size selectivity of fishing gear by conditioning on the total catch. J. Am. Stat. Assoc. 87: 962–968.
Millar, R.B. and Holst, R. (1997). Estimation of gillnet and hook selectivity using log-linear models. ICES J. Mar. Sci. 54: 471–477.
Millar, R.B. and Fryer, R.J. (1999). Estimating the size selection curves of towed gears,traps, nets and hooks. Rev. Fish Biol. Fisher. 9: 89–116.
Park, C.D., Jeong, E.C., Shin, J.K., An, H.C. and Fujimori, Y. (2004). Mesh selectivity of encircling gillnet for gizzard shad Konosirus punctatus in the coastal sea of Korea.Fish. Sci. 70: 553–560.
Sbrana, M., Belcari, P., de Ranieri, S., Sartor, P. and Viva, C. (2007). Comparison of the catches of European hake (Merluccius merluccius, L. 1758) taken with experimental gillnets of different mesh sizes in the northern Tyrrhenian Sea (western Mediterranean). Sci. Mar. 71: 47–56.
Valdéz-Pizzini, M., Acosta, A., Griffith, D.C. and Ruiz Perez, M. (1992). Assessment of the socio-economic impact of the fishery management options upon gillnet and trammel net fishermen in Puerto Rico: An interdisciplinary approach (anthropology and fisheries biology) for the evaluation of management alternatives. Final Report NOAA/NMFS, Grant #NA17FL0100-1. Unpub. MS.
Carol, J. and García-Berthou, E. (2007). Gillnet selectivity and its relationship with body shape for eight freshwater fish species. J. Appl. Ichthyol. 23: 654–660.
de Graaf, M., Machiels, M.A.M., Tesfaye Wudneh and Sibbing, F.A. (2003). Length at maturity and gillnet selectivity of Lake Tana‟s Barbus species (Ethiopia): Implications for management and conservation. Aquat. Ecosyst. Health 6 (3): 325–336.
de Graaf, M., Nentwich, E.D., Osse, J.W.M. and Sibbing, F.A. (2005). Lacustrine spawning: Is this a new reproductive strategy among „large‟ African cyprinid fishes? J. Fish Biol. 66:1214–1236.
De Silva, S.S., Schut, J. and Kortmulder, K. (1985). Reproductive biology of six Barbus species indigenous to Sri Lanka. Environ. Biol. Fish. 12: 201–218.
Dinçer, C.A. and Bahar, M. (2008). Multifilament gillnet selectivity for the red mullet (Mullus barbatus) in the Eastern Black Sea Coast of Turkey, Trabzon. Turk. J. Fish. Aquat. Sci. 8: 355–359.
Dos Santos, M.N., Gaspar, M., Monteiro, C.C. and Erzini, K. (2003). Gillnet selectivity for European hake Merluccius merluccius from southern Portugal: Implications for fishery management. Fish. Sci. 69: 873–882.
Erzini, K., Gonçalves, J.M.S., Bentes, L., Lino, P.G., Ribeiro, J. and Stergiou, K.I. (2003). Quantifying the roles of competing static gears: Comparative selectivity of longlines and monofilament gillnets in multi-species fishery of the Algarve (southern Portugal). Sci. Mar. 67: 341–352.
Gunderson, D.R., Callahan, P. and Goiney, B. (1980). Maturation and fecundity of four species of Sebastes. Mar. Fish. Rev. 42:74–79.
Hansson, S. and Rudstam, L.G. (1995). Gillnet catches as an estimate of fish abundance: A comparison between vertical gillnet catches and hydroacoustic abundances of Baltic Sea herring (Clupea harengus) and sprat (Sprattus sprattus). Can. J. Fish.Aquat. Sci. 52: 75–83.
Holden, M.J. and Raitt, D.F.S. (eds.) (1979). Manual of Fisheries Science. Part 2-Methods of Resource Investigation and their Application. FAO Fisheries
Technical Paper No. 115, Rev. 1, Rome, Italy.
Hovgärd, H. (1996). A two-step approach to estimating selectivity and fishing power of research gillnets in Greenland waters. Can. J. Fish. Aquat. Sci. 53: 1007–1013.
Hovgärd, H. and Lassen, H. (2000). Manual on Estimation of Selectivity for Gillnet and Longline Gears in Abundance Surveys. FAO Fisheries Technical Paper. No.397, Rome, Italy.
Kolding, J. (1999). PASGEAR. A Database Package for Experimental or Artisanal Fishery Data from Passive Gears. An introductory manual. University of
Bergen, Department of Fisheries and Marine Biology, Bergen, Norway.
Millar, R.B. (1992). Estimating the size selectivity of fishing gear by conditioning on the total catch. J. Am. Stat. Assoc. 87: 962–968.
Millar, R.B. and Holst, R. (1997). Estimation of gillnet and hook selectivity using log-linear models. ICES J. Mar. Sci. 54: 471–477.
Millar, R.B. and Fryer, R.J. (1999). Estimating the size selection curves of towed gears,traps, nets and hooks. Rev. Fish Biol. Fisher. 9: 89–116.
Park, C.D., Jeong, E.C., Shin, J.K., An, H.C. and Fujimori, Y. (2004). Mesh selectivity of encircling gillnet for gizzard shad Konosirus punctatus in the coastal sea of Korea.Fish. Sci. 70: 553–560.
Sbrana, M., Belcari, P., de Ranieri, S., Sartor, P. and Viva, C. (2007). Comparison of the catches of European hake (Merluccius merluccius, L. 1758) taken with experimental gillnets of different mesh sizes in the northern Tyrrhenian Sea (western Mediterranean). Sci. Mar. 71: 47–56.
Valdéz-Pizzini, M., Acosta, A., Griffith, D.C. and Ruiz Perez, M. (1992). Assessment of the socio-economic impact of the fishery management options upon gillnet and trammel net fishermen in Puerto Rico: An interdisciplinary approach (anthropology and fisheries biology) for the evaluation of management alternatives. Final Report NOAA/NMFS, Grant #NA17FL0100-1. Unpub. MS.
Published
2014-10-11
Section
Articles