New and revised catch forecasts for two-sea-winter Atlantic salmon (Salmo salar) in Icelandic rivers

Abstract

Summary Linear and multiple regression analysis was used to develop and improve models to forecast catches of two-sea-winter (2SW) Atlantic salmon (Salmo salar) from 43 Icelandic rivers. Catches of 2SW salmon in a given year were forecast based upon yields of grilse (fish that remain one year at sea) the previous year and upon three sea-temperature variables from hydrographic stations in western and northern Iceland. Highly significant relations (P<0.01) were found between grilse and 2SW salmon catches for 12 of 21 western rivers and 18 of 22 northern rivers. Nine of the 22 northern rivers had at least 60% of their variation in 2SW salmon catches explained by grilse catches the previous year. Because of collinearity between sea temperatures and grilse catches, little benefit was derived by adding sea temperature to the models based on grilse and 2SW salmon; in few rivers did the sea temperatures explain significant additional variation at <0.05.