Otolith microchemistry as a means of identifying stocks of deep-water demersal fishes (OTOMIC)

The deep-water fisheries of the North Atlantic and the Mediterranean have developed rapidly as traditional shelf fisheries decline. Most of the currently exploited species have very wide geographical ranges, which may place them within one or more of the designated management areas such as ICES, NEAFC and the Mediterranean. Many are also caught in international waters and come within the remit of 'straddling stocks and highly migratory species'. The assessment and management of these fisheries has many problems, including a lack of knowledge on stock identity. This problem is compounded because catch and effort data tend to be reported by statistical areas that were devised for shelf fisheries. If a fish lives in one or more water masses during its life then its otoliths will carry a chemical signature representative of these water masses. This chemical signature has been used to discriminate between stocks of shelf fishes. The objective of the OTOMIC project is to investigate the use of otolith microchemistry for stock discrimination in four deep-water fish species of the Atlantic and Mediterranean. Three of the species, the smooth grenadier (Mezumia aequalis), the bluemouth (Helicolenus dactylopterus) and the hake (Merluccius merluccius) are present in both the Atlantic and Mediterranean and have differing depth ranges and life history characteristics. The fourth species, the roundnose grenadier (Coryphaenoides rupestris), is widely distributed throughout the North Atlantic. Elemental composition of the otoliths was determined using solution-based and laser ICP-MS. This poster describes some of the preliminary results of the project.

Otolith microchemistry as a means of identifying stocks of deep-water demersal fishes (OTOMIC) (PDF Download Available). Available from: https://www.researchgate.net/publication/263104269_Otolith_microchemistry_as_a_means_of_identifying_stocks_of_deep-water_demersal_fishes_OTOMIC [accessed Mar 9, 2016].