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Potential Enhancement of Juvenile Mussel Production with Exogenous Cortisol Treatment of Fish Hosts
Author(s) -
Nelson Jace M.,
Bringolf Robert B.
Publication year - 2018
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1002/naaq.10014
Subject(s) - biology , metamorphosis , ictalurus , micropterus , unionidae , juvenile , mussel , zoology , fishery , oreochromis , blue mussel , nile tilapia , ictaluridae , rainbow trout , aquaculture , ecology , catfish , bass (fish) , larva , bivalvia , fish <actinopterygii> , mollusca
Hatchery propagation plays an essential role in restoration or augmentation of freshwater mussel populations, which are among the most critically imperiled of all taxa. A unique feature of freshwater mussel life history is an obligate parasitic relationship with fish in which the larval mussels (glochidia) must attach to host fish and metamorphose to the juvenile stage. Hatcheries can produce large quantities of juvenile mussels for restoration and research purposes; however, in cases where suitable host fish species have not been identified, options for propagation are severely limited. Although specific biochemical mechanisms mediating metamorphosis remain largely unknown, previous research suggests that the plasma cortisol level in the host is an important factor. Manipulation of cortisol to induce or increase metamorphosis in otherwise marginal or non‐host fish may provide a valuable tool in culturing mussel species for which the primary host(s) are unknown or prohibitively difficult to rear in a captive environment. The objective of the present study was to further investigate the potential for exogenous cortisol treatment to increase attachment and metamorphosis on marginal or non‐host fish. Cortisol treatment (intraperitoneal injection) of known host species (Largemouth Bass Micropterus salmoides and Bluegill Lepomis macrochirus ) did not affect attachment or metamorphosis; however, in non‐hosts (Channel Catfish Ictalurus punctatus and Goldfish Carassius auratus ) and marginal hosts (Blue Tilapia Oreochromis aureus × Nile Tilapia Oreochromis niloticus hybrids), attachment generally increased with increasing cortisol, though only significantly so in Goldfish. Metamorphosis was significantly increased on the marginal hosts but was not induced on the non‐hosts. This study provides clear evidence that cortisol manipulation of marginal hosts can increase juvenile mussel production and may be an important tool to maximize propagation efforts, particularly for imperiled species.