Growth, Survival, and Habitat Use of Naturally Reared and Hatchery Steelhead Fry in Streams: Effects of an Enriched Hatchery Rearing Environment

Abstract

After hatchery‐reared salmonids are released into the wild, their survival and performance are frequently lower than those of wild conspecifics. Additionally, negative effects of hatchery fish on wild fish are cited as factors affecting the recovery of salmonid populations. Alternative hatchery rearing environments and release practices have been proposed to mitigate both problems. We investigated the postrelease growth, survival, habitat use, and spatial distribution of hatchery steelhead Oncorhynchus mykiss fry reared in conventional and enriched environments and compared their performance with that of naturally reared steelhead fry from the same parent population in two streams. Average instantaneous growth rates differed between streams but not among the three rearing groups. The survival of naturally reared fry was significantly greater than that of both types of hatchery fry (relative survival = 0.33) but did not differ between the conventional and enriched environments. Naturally reared fry grew and survived equally well regardless of the type of hatchery fry with which they were stocked. Supplementation increased fry population size in all stream sections but produced hatchery‐biased populations. Steelhead fry preferred pool habitat within stream sections, but pool use was affected by an interaction between rearing environment and stream. Hatchery fry had more clumped spatial distributions than naturally reared fry, which were affected by a significant interaction between rearing type and stream. Hatchery rearing type and stream had no effect on the spatial distribution of naturally reared fry. We conclude that (1) hatchery steelhead fry released in streams grow as well as naturally reared fry but do not survive as well, (2) enriched hatchery environments do not improve postrelease growth or survival, and (3) upon release, fry raised in enriched hatchery environments affect the growth and survival of naturally reared fry in much the same way as fry reared in conventional hatchery environments.

Comparacion del crecimiento de Argopecten purpuratus entre cohortes obtenidas de captacion de larvas en ambiente natural y de hatchery

“…Para el cangrejo Scylla paramamosain, Ngoc-Ut et al (2007) reportaron que animales obtenidos en laboratorio presentaron mejores crecimientos que los de ambiente natural cuando fueron cultivados por separado, pero cuando se cultivaron en coexistencia esta diferencia fue anulada y no hubo diferencia en el crecimiento de ambos grupos. Este resultado sugiere la existencia de interferencia entre ambos grupos, de manera que el kiss), Tatara et al (2009) mostraron que no hubo diferencias significativas en el crecimiento entre truchas jóvenes obtenidas del medio y generadas en hatchery, mientras que Rhodes & Quinn (1999) mostraron evidencia que ejemplares de O. kisutch obtenidos en hatchery tuvieron mayor crecimiento que los obtenidos en el medio natural. El mismo resultado reportaron Siikavoupio et al (2009) para Salvelinus alpinus y Bates & McKeown (2003) para Oncorhynchus clarki clarki.…”

“…Los resultados han sido variados; así en cuanto a crecimiento, la evidencia muestra que las semillas obtenidas en el ambiente suelen crecer mejor que las de hatchery, al mismo tiempo que muestran una mayor supervivencia, aunque en algunos casos los resultados entre ambos tipos de semilla han sido similares. Para superar este menor desempeño, se han propuesto mejoras a la fase de producción en laboratorio (enriched hatchery), por ejemplo, ver Tatara et al (2009).…”

Steelhead return rates and relative costs: A synthesis of three long-term stocking programs in two Minnesota tributaries of Lake Superior

“…Evaluations of fry stocking through smoltification to adulthood are rare, and many studies of "fry" stocking actually involve juveniles reared well beyond the swim-up stage through various periods of feeding (e.g. Hume and Parkinson, 1987;Koenig et al, 2011;Tatara et al, 2009), thereby imposing additional hatchery selection. Survival rates of unfed fry, especially those originating from local wild stock, compare well with those of naturally spawned fish.…”

Using insights from animal behaviour and behavioural ecology to inform marine conservation initiatives

“…This may be because fish raised in hatcheries for release are often reared using commercial production techniques that do not emphasize preparation for the wild (Petersson, Camargo Valencia, & Järvi, 2014). Consequently, released fish can tend to exhibit reduced rates of growth, survival and impaired habitat use (Brown & Day, 2002; Tatara, Riley, & Scheurer, 2010), tend to be bolder, more aggressive and less experienced with predators than their uncultivated counterparts (Jackson & Brown, 2011; Sundström, Petersson, Höjesjö, Johnsson, & Järvi, 2004), and often have a limited ability to recognize, capture and handle wild prey (Brown & Day, 2002). This is similar to results from terrestrial reintroduction programmes, which suggest that captive-reared individuals tend to forage less efficiently (Ellis & Nash, 1998; Sol, Timmermans, & Lefebvre, 2002), demonstrate poorer antipredator behaviours (Alvarez & Nicieza, 2003; Armstrong & Seddon, 2007; Fischer & Lindenmayer, 2000; Koolhaas et al, 1999) and are less adept at finding quality territories (Deverill, Adams, & Bean, 1999; Mathews, Orros, McLaren, Gelling, & Foster, 2005) than their wild counterparts.…”