Dataset Information

The effects of environmental enrichment on hatchery-performance, smolt migration and capture rates in landlocked Atlantic salmon.

ABSTRACT: Enrichment of rearing environment with natural elements has been suggested to improve the welfare and post-release survival of cultured fish. We studied the combined effects of shelter structures, periodical water flow and water level changes on pre- and post-release performance of critically endangered landlocked Atlantic salmon (Salmo salar m. sebago). Relative to standard (plain) rearing tanks, provision of enrichment improved fish condition factor and survival during the first year of rearing when most mortality was attributable to parasitic and bacterial infections. The consequent higher density in enriched tanks probably induced greater growth variation and more dorsal fin damages than found in fish of standard tanks. Possibly this was partly due to the applied changes in water level. Experimentally determined smolt migration tendency at age 3 did not differ, on average, between the rearing groups, but enriched-reared fish showed clearly less variation in total movement activity than standard-reared fish. Experimental angling in earthen ponds did not suggest divergent vulnerability between the differentially reared fish at age 3, but decreased condition during the preceding growth season increased vulnerability to fishing. Based on long-term post-stocking tag returns in large-lake fisheries, fish length at release but not rearing method affected the capture rates of fish released at age 2. When released at age 3 the fish grown in enriched environment had a higher risk to be captured with stationary gears and earlier by hook and line gears compared to standard-reared conspecifics. Earlier time of maximal smolt migration activity was associated with an increased risk of being captured. We suggest that environmental enrichment may modulate growth- and behavior-related qualities that indirectly increased the vulnerability to fishing in natural conditions but not in experimental setting. The favorable effects of enrichment on early survival encourages adopting enriched rearing practices in supportive breeding of landlocked salmon.

SUBMITTER: Janhunen M

PROVIDER: S-EPMC8638868 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Increased knowledge of heritable traits in Atlantic Salmon (Salmo salar) is important to overcome bottlenecks in salmonid aquaculture. Atlantic salmonid populations, both landlocked and anadromous, represent an interesting model to gain insight into anadromy related traits, most notably, the probability to smoltify. While a previous study has identified several genomic regions diverging between anadromous and landlocked populations across the species range, the present study explores these data further with the aim to uncover if some of these genomic regions are linked to beneficial genetic traits associated with smoltification. In this study 17 of these loci were monitored in 669 anadromous salmon originating from 36 full-sibling families that had been reared under common garden conditions. The Smolt Index was calculated, using multiple visual markers, and provided a means of assessing smoltification stage. One SNP, located in Ssa04, showed a significant association with probability to smoltify, where individuals homozygous for the landlocked variant (LL) displayed a decrease in probability of smoltifying after one winter when compared with the homozygous for the anadromous variant (AA). This effect was independent of individual fish size. A separate common garden study comprising 200 individuals from either anadromous or landlocked strains showed that expression levels of ncor1, a thyroid mediator hormone located on the same chromosomal region (Ssa04), were significantly reduced in landlocked individuals post smoltification but remained constant in their anadromous counterparts. This study therefore suggests that while size is still the most important trigger for the induction of smoltification, there may also be an additional genetic component or trigger that has been 'lost' during the years deprived of SW transfer. In conclusion, the LL genotype identified here could potentially be used by the industry to delay smoltification and may also represent one of the first clues to the genetic regulation of smoltification in Atlantic salmon.

Project description:Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs: in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing at the level of the transcriptome in Atlantic salmon (Salmo salar). Full siblings were reared in either a M-bM-^@M-^\simpleM-bM-^@M-^] environment devoid of structure or a M-bM-^@M-^\complexM-bM-^@M-^] environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcription in head tissues using the cGRASP-designed Agilent 4M-CM-^W44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented, several of which are associated with mitosis/cell cycle and muscle and heart development. However, there were also pronounced differences among families in gene transcriptional response to rearing environment, with the number of genes significantly differentially transcribed by juveniles in our independent analyses of each family ranging from zero to 3445 (FDR of 5%). Overall, our results suggest that rearing environment enrichment can profoundly change patterns of gene transcription during salmon development, but that the degree of response depends on genetic background. This was a two-condition experiment in which a total of 30 RNA samples isolated from the heads of developing salmon were analysed: 15 juveniles reared in a traditional hatchery environment and 15 reared in a hatchery environment enriched with gravel substrate.

Dataset Information

The effects of environmental enrichment on hatchery-performance, smolt migration and capture rates in landlocked Atlantic salmon.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets