Modelling of unexploited and exploited populations of eels, Anguilla anguilla (L.), in the Thames Estuary

• Published in: Journal of Fish Biology
• Main Authors: Naismith, I. A., Knights, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1990
• Subjects: Anguilla anguilla
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1990.tb03600.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1990.tb03600.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1990.tb03600.x

Eels were fyke‐netted in different zones of the Thames Estuary at various times of year and subsamples sexed, aged and stomachcontentsexamined. Instantaneous mortality coefficients (Z) were calculated for each 3 cm length class for eels > 30 cm and used to construct a compartmental model to assess effects of natural and fishing mortality and migration on different life stages of males and females. Growth rates were good and fishing mortality effects low and masked by effects of emigration/immigration (and, possibly, local migrations). Density‐dependent mortality appeared to be having minor effects. Males dominate freshwater sites, females the more saline zone and possible implications of food availability and density are discussed. It is concluded the stock is not being over‐exploited but that elver recruitment is relatively low. Means of increasing exploitation are discussed, as are ways of increasing production of females to enhance elver recruitment to the Thames and other European rivers.