Hepatoxylon trichiuri (Cestoda: Trypanorhyncha) plerocercoids in cage-reared northern bluefin tuna, Thunnus thynnus (Osteichthyes: Scombridae)
Northern bluefin tuna (Thunnus thynnus) were caught by purse seine boats and brought to a farm for a rearing cycle of 1.5 years. Mortalities occurred in the first weeks of acclimatization at the facility. Parasitological examination revealed plerocercoids of the cestode Hepatoxylon trichiuri embedded in the stomach mucosa. The larvae were found in 28.4% of the fish and the mean abundance was 3.12 per fish. Histopathology revealed disseminated erosion at the site of attachment, atrophy of fundic glands, lymphocytic migration, and hyperplasia of connective tissue in the lamina propria. These symptoms, however, together with the parasite abundance, could not have triggered the mortalities. This is the first record of this parasite in northern bluefin tuna.
Endoparasite fauna of five Gadiformes fish species from the coast of Chile: host ecology versus phylogeny
Abstract The aims of the present study were to compare, using multivariate analyses, the degree of similarity of the endoparasite fauna of five fish species belonging to the order Gadiformes: Merluccius gayi, Merluccius australis, Macruronus magellanicus (Gadoidei) and Micromesistius australis and Nezumia pulchella (Macrouroidei), from the southern and central Chilean coast, and to evaluate whether the composition of the endoparasite fauna was determined by phylogenetic or ecological relationships. We employed our database of Merluccius australis, M. magellanicus and Micromesistius australis, which was complemented with published information for M. magellanicus, Merluccius australis, Micromesistius australis, M. gayi and N. pulchella. A higher number of endoparasite species was recorded for Merluccius australis, Micromesistius australis and M. magellanicus, namely Anisakis sp. and Hepatoxylon trichiuri, which is the most prevalent parasite among these hosts. Aporocotyle wilhelmi and Hysterothylacium sp. were detected only in M. gayi, whereas Lepidapedon sp. was found exclusively in N. pulchella. These results suggest that fish ecology rather than host phylogeny was the most important factor for the determination of similarity in parasite composition. This result could be explained by the similar trophic patterns of hosts and by the predominance of generalist larval species among these fish parasite communities.
A survey of aquaculture production economics and management
Abstract The literature on production economics and management of fish culture has grown as aquaculture has matured as a commercial industry. Salmon, catfish, shrimp and trout are the focus of this literature survey as a reflection of the volume of research that has been completed on these species and their importance in US production and world trade. In addition, a discussion of low resource production systems is included that is dominated by tilapia and carp culture systems. A brief overview of the principles of aquaculture production economics and management is presented followed by a review of economic studies.