Effects of water temperature on year-class strengths and growth patterns of pikeperch (Sander lucioperca (L.)) in the brackish Baltic Sea

Abstract

Pikeperch (Sander lucioperca), the studied species, is the most important amongst freshwater fish species, commercially, in the brackish Baltic Sea. We studied the effects of water temperature on three aspects of pikeperch growth in Haminanlahti bay, Finland. First, annual length increments were related to age and temperature using a non-linear growth model. Since length increments were based on backcalculated lengths, i.e. repeated measurements, the first order autoregressive covariance structure was used. The model showed that when temperature increased annual length increments also increased, whereas increased age reduced annual length increments. In the modelling, the best fit was found with water degree-days over 10°C. Second, the onset of growth of pikeperch in spring had a positive relationship with water temperature and a negative one with the length of pikeperch. The latter finding suggests that smaller, non-mature pikeperch starts to grow earlier than larger, mature pikeperch. Third, the year-class strength was positively correlated with water degree-days, and the year-class strength negatively affected annual length increments. This indicates that within a strong year-class subsequent growth is reduced more that within a weak year-class, suggesting density-dependent growth.

Climate Warming and Pikeperch Year-Class Catches in the Baltic Sea

“…The coefficients of determination between real and modeled water temperatures were 0.8 for GoF and 0.9 for AS (Table 1). These are comparable with earlier results using the same model (Kjellman et al 2001(Kjellman et al , 2003Lappalainen et al 2009). …”

“…Such a gradual recruitment is based on large variation in growth rates. These growth patterns can also be explained by the annual variations in water temperature (Lappalainen et al 2005(Lappalainen et al , 2009.…”

Management of pikeperch stocking in Lake Balaton: effect of season, area, fish size and method of release on the rate and distribution of recaptures

“…On the other hand, due to overexploitation of adults and loss of natural spawning and nursery areas reproductive success of pikeperch populations is falling and now often fails to meet ecological and economic demands (Saulamo and Thoresson, 2005;Specziár and Erős, 2016). Exposure of pikeperch recruitment to adverse human impacts is also enhanced by the high sensitivity of spawning success, and early life and first wintering survival of this species to year-to-year variations of environmental conditions (Ruuhijärvi et al, 1996;Lappalainen et al, 2009). Therefore, there is an increasing need to compensate these adverse effects by stocking of aquaculture-reared individuals (Hansson et al, 1997;Abdolmalaki and Psuty, 2007).…”

Challenges and Opportunities of Local Fisheries Management: Pikeperch, Sander Lucioperca (Actinopterygii: Perciformes: Percidae), in Pärnu Bay, Northern Gulf of Riga, Baltic Sea

“…Pikeperch cannibalism is also well known from lakes, especially at high juvenile density (Frankiewicz et al 1999, Lappalainen et al 2006), but has so far not been documented in Pärnu Bay. Intraspecific competition between juveniles in strong yearclasses has also been suggested to make pikeperch recruitment density-dependent (Lappalainen et al 2009). …”

“…The maximum stock size used to construct the stock-recruitment model was 720 t, implying that a large part of the stock sizes simulated in scenarios beneficial to pikeperch reproduction (high goby abundance, expected climate change) are outside the range for which the stock-recruitment relation has been calibrated. Lappalainen et al (2009) have suggested that density dependent effects on recruitment might increase in a warmer climate, making the effect of climate change on pikeperch populations more complex. Further, our model does not take into account whether Pärnu Bay can provide enough food for a doubled or tripled pikeperch population.…”