We determined the hatch dates of young-of-year (YOY) juveniles from the 1995 to 1999 year-classes of haddock Melanogrammus aeglefinus collected in the Northeast Fisheries Science Center fall groundfish surveys in the Gulf of Maine/Georges Bank region. Hatch dates were based on age estimates made by counting otolith daily rings. The average YOY haddock was > 200 d old at the time of capture, with estimated hatch dates ranging from mid November to early June. Haddock collected in the Gulf of Maine had mean hatch dates about 1 mo later than fish collected on Georges Bank. Each year on Georges Bank, hatch date frequencies (HDF) of survivors peaked between February and mid March, considerably earlier than the peak in HDF estimated from late-stage eggs. The ratio of the relative HDF of survivors collected in the fall to the relative HDF estimated from late-stage eggs was used to calculate relative survivorship of different cohorts. These data suggest that haddock hatched early in the season had a survival advantage over those hatched later in the year. The 1998 year-class, the largest produced on Georges Bank in the past 20 yr, had one of the latest peaks in HDF of juveniles among the 5 years examined. More survivors were produced in each month of 1998 compared to the monthly averages of the remaining years. In particular, the 1998 year-class benefited from enhanced survival of individuals hatched in the mid and latter portions of the hatch curve, although survival was still highest for individuals originating from the early portion of the hatching curve. KEY WORDS: Georges Bank · Hatch date distributions · Juvenile haddock · Otolith microstructure · RecruitmentResale or republication not permitted without written consent of the publisher

In an e¡ort to optimize the e⁄ciency of high-density incubation of Atlantic cod Gadus morhua and haddock Melanogrammus aegle¢nus eggs, the per cent hatch of eggs treated with four disinfectants (3% hydrogen peroxide, 1% polyvinylpyrrolidone iodine, 0.1% sodium hypochlorite and a 0.005% antibiotic solution^penicillin/streptomycin) was compared in both species. The per cent hatch of eggs of each species was greatest after a 24 h treatment with the antibiotic solution. The hatching success of eggs treated within the di¡erent disinfectant treatments depended upon the embryonic developmental stage in both species. The sodium hypochlorite treatment had the lowest % coverage of colony growth after disinfected haddock eggs were plated onto sterile agar media, highest survival rates to the end of the embryonic period, but the lowest per cent hatch.

Seasonality becomes more pronounced with increasing latitude, so that at northern sites organisms must adapt to a shorter growing season and more extended and severe overwintering conditions. Narragansett Bay (Rhode Island, USA) lies near the northern extent of the range of the bay anchovy Anchoa mitchilli, an abundant member of this estuarine system during the summer months. The length of the spawning season, hatch-date frequency, and young-of-the-year (YOY) growth rates were evaluated for Narragansett Bay anchovies during the summer of 1997 by gonadosomatic indices (GSI) and otolith-increment analysis. GSI data indicated a shorter spawning season for this species in Narragansett Bay than at lower latitudes. Otolith-increment analysis data indicated that hatch-datefrequency was highest in July. Mean YOY growth rate (0.70 mm d ). One possible adaptation to a shorter growing season is an increased growth rate during favorable conditions.

Population structure, growth and mortality of Anchoa mitchilli were evaluated in Narragansett Bay (Rhode Island, USA), an estuary near the northern extent of this species' broad latitudinal range. The Narragansett Bay population was dominated by young fish (Age 1 and young-ofthe-year, YOY); no fish were found to have survived a third winter. Growth rates were rapid, particularly during the first year of life, and annual mortality rates were estimated at > 90%. A von Bertalanffy growth model fit to length-at-age data yielded parameters of asymptotic length L ∞ = 89.97, growth coefficient K = 1.15 and age at zero length t 0 = -0.31. Comparison of my results to those of an earlier study from Chesapeake Bay suggests that Narragansett Bay anchovies grow more rapidly during the first year of life, and subsequently attain a greater length-at-age, than their conspecifics at lower latitudes. Latitudinal differences are also indicated by comparison of the weightlength relationships and Fulton's condition factors of Narragansett Bay and Chesapeake Bay data. Narragansett Bay fish seem to be allocating energy preferentially to length versus weight compared to fish in Chesapeake Bay, which may be a reflection of this species' growth strategy at this latitude.