Year-class strength of plaice Pleuronectes platessa in the Southern Bight of the North Sea:a validation and analysis of the inverse relationship with winter seawater temperature

Abstract

[1974][1975][1976][1977][1978][1979][1980][1981][1982] observed inverse relationship between the February seawater temperature at the spawning grounds in the Southern Bight of the North Sea and subsequent year-class strength of 0-group plaice on the Balgzand tidal flats (western Dutch Wadden Sea) was revalidated for the period 1991-1998 However, seawater temperatures deternuned from NOAA satellite images showed that water temperatures during egg and larval drift in the open sea were more constant than the February temperatures at the spawning grounds suggested. In all years, and under all conditions, there was a persistent tongue of Engl~sh Channel water entenng through the Dover Strait into the Southern Bight of the North Sea, In which plaice eggs and larvae developed and were transported The intensity of this plume varied between years, but even during the coldest penod it penetrated as far as offshore Texel and the Marsdiep inlet. The absence of interruptions in the pattern of larval immigrations at the nursery implies a link between variations in water temperatures and in the period of drift Between and within years, the number of settling larvae at Balgzand was mversely related to the median temperature dunng drift. Overall, also year-class strength estimates were stlll inversely related to water temperature during drift. However, the relationship broke down for the very strong 1996 yearclass, suggesting that other factors were acting too. Cold winters (reflected in low temperatures in the coastal zone) are associated with persistent winds from the east which induce a n atypical water circulation pattern that affects the strength and direction of the residual current Easterly winds might also generate upwelling near the coast stimulating larval immigration.

Larval distribution of offshore spawning flatfish in the Gulf of Alaska: potential transport pathways and enhanced onshore transport during ENSO events

“…For some marine species, spawning occurs in the vicinity of suitable nursery habitats, and retention of eggs and larvae is a favorable condition for recruitment (Sinclair 1988). Other species may spawn outside of nursery areas, and successful recruitment depends on transport to the nursery habitat (Van der Veer et al 1998, Van der Veer & Witte 1999). Offshore spawning flatfish species whose juvenile nurseries are inshore are of the latter type, and in general, most flatfish species have juvenile nurseries that are inshore of the spawning area (Minami & Tanaka 1992).…”

Distribution and abundance by larval developmental stages of <em>Symphurus williamsi</em> (Pleuronectiformes: Cynoglossidae) in the Gulf of California

“…The principal reproductive strategies reported in pleuronectiforms are: 1) species that spawn in or near suitable nursery habitats where retention of eggs and larvae is favourable for recruitment, and 2) species that spawn far from their nursery habitats ( Van der Veer et al, 1998;Van der Veer and White, 1999;Bailey and Piquelle, 2002). Most flatfish are the latter type (Minami and Tanaka, 1992), as seen in the Gulf of California for S. ovale (Aceves-Medina et al, 2003b) and S. williamsi.…”

Physical influences on the stock dynamics of plaice and sole in the North Sea

“…Such meristic characters are known to vary with temperature and other environmental factors during egg and larval development (Lindsey, 1988). The year in which the samples were taken (1995), however, was unusually stable in temperature during the season of egg and larval drift (van der Veer and Witte, 1999), and the composition of incoming larvae by groups was fairly homogeneous through the season. Therefore, the findings do not point convincingly to temperature as a driving factor, but there must be some other variables besides temperature operating during early development which have significant effects on the early juveniles.…”

“…The year class strength of plaice is inversely related to water temperature at the spawning ground (van der Veer and Witte, 1999); the abundance of 0-group plaice in the German Bight is negatively correlated with temperature during gonadal maturation and during the first egg stages (Lange and Greve, 1997). Delay in spawning time and development caused by low temperature gives better survival chances when entering the nursery areas due to the more delayed predator development (van der Veer and Witte, 1999).…”

“…Delay in spawning time and development caused by low temperature gives better survival chances when entering the nursery areas due to the more delayed predator development (van der Veer and Witte, 1999).…”