The Effect of Grading on the Total Weight Gained by Three Species of Trout

Pyle, Earl A.

doi:10.1577/1548-8640(1966)28[29:teogot]2.0.co;2

Cited by 5 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several authors [35][36][37][38][39][40][41] have reported improvements in overall weight gain or survival of aquaculturally-reared fish that have been subjected to grading. However, the use of grading is not supported by Kamstra [39], Pyle et al [42][43][44], Sunde et al [45], Wallace and Kolbeinshavn [46], Carmichael [47], Strand and Øiestad [48], Makinen and Ruchonen [49], and Onders et al [50]. The lack of effect by grading in the prior studies may be due to the ineffectiveness of grading to eliminate dominance hierarchies and aggression [35].…”

Section: Discussionmentioning

confidence: 99%

Competitor Density and Size Effects on Aggression and Feeding in Cutthroat Trout: Implications for Aquaculture

Barnes¹

2011

TOFISHSJ

View full text Add to dashboard Cite

Competitor density and aggressive behavior influences the ability of fish to use food resources during aquaculture production. Using cutthroat trout Oncorhynchus clarkii (Richardson) from the same filial generation, this study investigated the effects of both body size and rearing density on aggression and feeding behavior. Four experiments were conducted using different numbers of both small and large trout obtained after grading. In each experiment, regardless of the number of each size of fish, small fish made significantly fewer attempts to forage in comparison to large fish. However, the number of aggressive interactions increased as small fish densities increased. These results suggest that grading and rearing differently-sized fish separately during rearing will likely maximize growth and rearing efficiencies in wild-strain cutthroat trout during hatchery rearing.

show abstract

Section: Discussionmentioning

confidence: 99%

Competitor Density and Size Effects on Aggression and Feeding in Cutthroat Trout: Implications for Aquaculture

Barnes¹

2011

TOFISHSJ

View full text Add to dashboard Cite

show abstract

“…Indeed, grading effectively decreased the variation in size and increased the mean size of hatchery Yellow Perch Perca flavescens (Wallat et al 2005), and it also increased the growth of hatchery Brown Trout Salmo trutta (Brown 1946) and Atlantic Salmon S. salar (Gunnes 1976). However, other studies have found grading to have no growth benefit for Arctic Char Salvelinus alpinus (Wallace and Kolbeinshavn 1988) or for Brown Trout, Brook Trout Salvelinus fontinalis, and Rainbow Trout Oncorhynchus mykiss (Pyle 1966).…”

mentioning

confidence: 99%

“…Size grading is one method that could be used to select for larger fish from a given rearing unit. Literature on fish grading and its effect on hatchery rearing date back to the mid‐1900s (e.g., Brown ; Mullan ; Pyle ), and grading practices continue to be used as a tool for rearing hatchery trout by some state agencies (Mark Clifford, State of California Department of Fish and Game, personal communication; Kris Urquhart, Nevada Division of Wildlife, personal communication). Hatcheries grade fish to achieve a uniform size, to reduce cannibalism in certain species, and to increase the accuracy of weight estimates by reducing size variation during sample counts.…”

mentioning

confidence: 99%

The Effect of Raceway Grading on Return to Creel for Catchable‐Sized Hatchery Rainbow Trout

Meyer

Cassinelli

2020

N American J Aquac

View full text Add to dashboard Cite

Hatchery trout of catchable size (i.e., about 250 mm total length; hereafter termed "catchables"), which are stocked into put-and-take fisheries, are expensive to raise, so fisheries management agencies strive to modify rearing practices to maximize the proportion of stocked catchables that anglers catch. We graded fish in production-level hatchery rearing units at both fingerling and catchable size, dividing the fish into "leaders" (herein, the larger fish in a rearing unit, separated during a grading event) and "laggers" (the smaller fish). We hypothesized that (1) grading and immediate stocking of catchable leaders and short-term retention and continued feeding of catchable laggers might increase lagger growth and result in a larger average size of fish being stocked (relative to fish from ungraded raceways), potentially improving overall return to creel for the graded group and (2) grading and separation of fingerling leaders and laggers early in the rearing process may reduce competition between smaller and larger fish for the remainder of the rearing period, potentially improving overall poststocking return to creel for the entire group without the need for catchable grading at the time of stocking. We found that grading catchables just prior to stocking slightly increased the mean size at stocking (compared with ungraded control fish) for the first stocking period, which resulted in slightly higher return to creel for stocked fish. However, across the entire stocking period and with equal feed between groups, mean size at release was nearly identical between the graded and the control fish, as was return to creel by anglers. Grading fingerlings to separate leaders and laggers for the remainder of the rearing period also had no positive effect on angler catch. Our findings suggest that production-level grading is ineffective at increasing the growth of laggers, so it will not increase overall size at stocking. Consequently, improvements in angler catch are unlikely to materialize from grading hatchery trout prior to stocking them into put-and-take fisheries.Stocking catchable-sized hatchery trout (i.e., about 250 mm total length [TL]; hereafter termed "catchables") into put-and-take fisheries has long been used to create recreational fisheries in waters that cannot support wild trout or can support so few that no trout fishery would exist without the stocking program (Butler and Borgeson 1965;Johnson et al. 1995). While such fisheries are popular among anglers (Park 2007;Hunt et al. 2017), raising catchables is expensive (Johnson et al. 1995;Hunt et al. 2017;Losee and Phillips 2017). Thus, maximizing the proportion of stocked catchables that anglers catch is a common goal for fisheries management agencies that are engaged in such hatchery programs.The postrelease performance of catchable trout (in terms of angler catch) can be influenced by the conditions that they face both prior to and after stocking. Numerous studies have reported about the influence of hatchery rearing practices on the postrelease perfo...

show abstract