Factors affecting the post‐release survival of cultured juvenile Pseudopleuronectes americanus

Abstract

Laboratory experiments were performed with cultured and wild juvenile winter flounder Pseudopleuronectes americanus to evaluate differences in behaviour and adaptation affecting post-release vulnerability to predation. Studies revealed that the cryptic abilities of cultured winter flounder increased over time. Sediment-naı¨ve, cultured fish required a minimum of 2 days to improve their burying skills and at least 90 days for colour adaptation to match the sediment. Cultured winter flounder selected sediments consisting of small grains and colours matching their own pigment. Cultured winter flounder, regardless of their colour, were significantly more vulnerable to predation by birds. Additionally, cultured fish reacted differently than wild winter flounder when exposed to cues from a potential predator. # 2004 The Fisheries Society of the British Isles

Benthic fish exhibit more plastic crypsis than non-benthic species in a freshwater spring

“…The background matching that we observed for L. parva was similar to the response elicited for other banded species on black and white backgrounds, such as Fundulus heteroclitus, although the authors of these reports did not provide any discussion of a changing banding pattern (Matthews 1933;Hill et al 1935;Pye 1964). The change in the banding pattern was much more subtle than the dynamic cryptic responses of tropical flatfish, cuttlefish, and octopi (Ramachandran et al 1996;Hanlon et al 1999;Fairchild and Howell 2004;Barbosa et al 2007), and it differed from the wide and dark saddle patterns of the hogsuckers, suckers, madtoms, sculpins, and darters described as disruptive coloration by Armbruster and Page (1996). However, it likely serves a similar function.…”

“…We observed permanent crypsis (countershading and disruptive coloration) and induced crypsis (rapid background matching), as well as both processes concurrently (countershading that darkened to match the background). Countershading, benthic background matching, and disruptive coloration can decrease predation pressure by reducing detection by predators (Sumner 1935;Donnelly and Whoriskey 1991;Fairchild and Howell 2004;Manríquez et al 2008). Blue Spring has extremely clear water with high visibility, and crypsis is undoubtedly particularly important in this system.…”

“…Juveniles of many organisms are more cryptically colored through their vulnerable sizes or stages than adults of the same species (Donnelly and Dill 1984;Graf and Nentwig 2001;Manríquez et al 2008), but juvenile crypsis may be enhanced by matching the lighting environment as well as the background color and pattern. Juveniles raised on darker backgrounds or in lower light may appear darker than juveniles reared on lighter backgrounds or in higher light (Donnelly and Whoriskey 1991;Fairchild and Howell 2004). Coarse color change also may be induced in adult organisms with long incubation periods.…”

“…These responses are rapidly inducible, but also reversible. In the most dramatic cases, tropical flatfishes and cephalopods change their color intensity and/or pattern to match differently colored or heterogeneous substrates, such as checkerboard patterns (Ramachandran et al 1996;Chiao and Hanlon 2001;Fairchild and Howell 2004;Kelman et al 2006;Ruxton et al 2004a;Barbosa et al 2007). Less plastic species can elicit more subtle changes in the intensity and/or hue of skin coloration through hormonal control or a combination of neurological and hormonal control (Fries 1942;Pye 1964;Fujii 2000).…”

Effect of shelter acclimation on the post-release movement and putative predation mortality of hatchery-reared black-spot tuskfish Choerodon schoenleinii, determined by acoustic telemetry

“…Both field and laboratory experiments on flounder species suggest that pre-release habitat acclimation benefits hatchery-reared fish by allowing them to adjust to the wild habitat, thus decreasing post-release predation mortality [7][8][9][10].…”