Estimating the entangling effect of trammel and semi-trammel net selectivity on rainbow trout (Oncorhynchus mykiss)

Size selectivity of trammel nets in southern European small-scale fisheries

“…The selectivity curve of trammel nets is domed but has a flatter shape than that for fin-fish caught with gill nets, as reported by authors who used the same methodology to fit the selectivity curve (Koike and Matuda, 1988;Losanes et al, 1992a). If a significant proportion of individuals, especially the larger ones, are pocketed or trammelled, then the selectivity curve may not fall to zero or even have a descending limb, implying that very few fish escape after coming into contact with the trammel net (Salvanes, 1991;Losanes et al, 1992b).…”

“…This is known as trammelling or pocketing (Losanes et al, 1992b;Fabi et al, 2002). The catches of trammel nets depend primarily on the mesh size and vertical slack of the inner net (Purbayanto et al, 2000) with several studies reporting wider selection ranges with increasing inner net slackness (Kitahara, 1968;Koike and Takeuchi, 1985;Koike and Matuda, 1988;Salvanes, 1991;Losanes et al, 1992a,b).…”

“…Fujimori et al (1996) also use Kitahara's (1968Kitahara's ( , 1971) method and report a dome-shaped selectivity curve that is flat on top. Losanes et al (1992b) fit a bi-normal curve where the first component is assumed to correspond to fish that are essentially gilled or wedged, as in gill nets, and the second one to larger fish that are entangled or trammelled/pocketed. Matsuoka (1991) reports that trammel net selectivity for Tilapia mossambica is bi-modal, with wedging being a minor component compared to entangling.…”

“…However, this is often not practical given the difficulty and subjectivity in identifying the primary method of capture. Thus, fitting a bi-modal curve to the data for all fish captured, irrespectively of the method of capture, may be more correct (Losanes et al, 1992b). Direct estimation of size selectivity for trammel nets has been reported by several authors (Fujimori et al, 1990(Fujimori et al, , 1992Matsuoka, 1991;Salvanes, 1991;Losanes et al, 1992b).…”

Mesh selectivity of gill net for female Japanese sandfish (Arctoscopus japonicus) in spawning season

“…, , (Losanes, 1992;Fujimori et al, 1996;Tokai et al, 1996;Wileman et al, 1996;Cho et al, 2000;Kim and Lee, 2002;Park et al, 2003Park et al, , 2004aPark et al, 2004bPark et al, , 2007Jo et al, 2006). (39.4, 45.5, 51.5, 53.0, 57.6mm (Kitahara, 1968).…”