Marion Claireaux and herring life history

Marion has been analysing herring data in order to understand how fishing might have influenced the life history of this ecologically and commercially important species. Previous studies have shown that maturation in this stock has fluctuated, but there seem to be little evolutionary change in the underlying maturation tendency (Engelhard & Heino 2004 MEPS). The results by Marion point to the direction of changes in reproductive investment and growth, although also these are relatively small. In addition, she has studied selection on herring using the scale growth rings, in homage to Rosa Lee. On top of all the data-driven work, Marion has also used modelling to understand how gear selection on bahviour might affect life history in a somewhat less herring-like fish.

The thesis consists of a synthesis and four chapters:

• Claireaux, M., Jørgensen, C., and Enberg, K. 2018. Evolutionary effects of fishing gear on foraging behavior and life-history traits. Ecology and Evolution, 8: 10711–10721. doi:10.1002/ece3.4482.
• Claireaux, M., dos Santos Schmidt, T.C., Olsen, E.M., Varpe, Ø., Slotte, A., Heino, M., Enberg, K. (In prep). Eight decades of changes in herring reproductive investment: effects of fishing, environment and conspecific density. (submitted)
• Claireaux, M., Folkvord, A., Heino, M., Enberg, K. (In prep). The Rosa Lee Phenomenon revisited: Population dynamics, sampling and selectivity affect the apparent changes in growth rate. (manuscript)
• Claireaux, M., Zimmermann, F., Ernande, B., Heino, M., Enberg, K. (In prep) Reconstructing growth in Norwegian spring-spawning herring from scale increments: exploring historic population dynamics and their drivers. (manuscript)

The opponents were Anna Gårdmark from SLU, Sweden, and Fredrik Jutfelt from NTNU, Trondheim. The thesis was supervised by Katja Enberg (BIO, until 8/2018 IMR, main supervisor) and Mikko Heino (EvoFish).