Elizabeth A. Fairchild

Using Telemetry to Monitor Movements and Habitat Use of Cultured and Wild Juvenile Winter Flounder in a Shallow Estuary

Home ranges, dispersal patterns, and habitat associations of juvenile winter flounder (Pseudopleuronectes americanus) were studied using acoustic tags and three tracking systems in the Hampton-Seabrook Estuary in New Hampshire, USA. This is the first study that we know of to use electronic tags on juvenile winter flounder, and on flatfish ≤ 19 cm.

Predators Are Attracted to Acclimation Cages Used for Winter Flounder Stock Enhancement

Acclimation cages are used for juvenile, cultured winter flounder Pseudopleuronectes americanus so that the fish can adjust to their new environment, hone their burial skills, begin pigment change, and recover from the stress of transport to the release site, all in the absence of predation. However, there have been indications that the cages attract the predatory green crab, Carcinus maenas. Studies conducted at the release site in the Hampton-Seabrook Estuary, New Hampshire, USA, determined that green crab abundance was significantly higher (ANOVA, p < 0.01) on cages containing fish than on empty cages, proving that acclimation cages containing flounder do attract green crabs. In addition, when empty acclimation cages were deployed, crab densities significantly increased (ANOVA, p < 0.01) in the vicinity of the acclimation cages and continued to increase each day, indicating that green crabs are also attracted to empty cages. Thus, although acclimation cages are a necessary tool that allows the stocked fish to adjust to their new environment, they also may be a detriment if they attract predators to the site. Using active adaptive management, release strategies must be reevaluated to reduce such predator-prey encounters, thereby improving fish survival.

The green crab Carcinus maenas in two New Hampshire estuaries. Part 1: spatial and temporal distribution, sex ratio, average size, and mass

The spatial and temporal distribution of the green crab, Carcinus maenas (Linnaeus, 1758) was studied in two New Hampshire estuaries, NW Atlantic, over a one-year period from November 2009 to October 2010 using baited traps. Green crab catch peaked in December and March in the Great Bay Estuary (GBE), and in November and April in the Hampton-Seabrook Estuary (HSE). Catch per unit effort was higher in the HSE than in the GBE, and more than 14 times as many green crabs were captured in the HSE (n = 35 788) than in the GBE (n = 2337). Catch of green crabs generally rose with increasing distance up-estuary in the HSE, while in the GBE, catch peaked mid-estuary. Quantity and species diversity of by-catch was greater in the GBE than in the HSE. In the HSE, sex ratios were skewed toward females in summer and female catch was maximized in salinities 30-31 ppt. In both estuaries, sex ratios favored male crabs most in the spring (March-April). Male and female green crabs in the GBE were larger (carapace size, weight), on average, than those in the HSE. This is the first study to compare seasonal green crab populations throughout and between NH estuaries.

Indications of Offshore Spawning by Southern Gulf of Maine Winter Flounder

AbstractThis is the first study to document quantitatively that Gulf of Maine (GOM) Winter Flounder Pseudopleuronectes americanus spawn offshore. Three sites (southern Jeffreys Ledge, Bigear [an area southwest of Tillies Bank], and a portion of Stellwagen Bank National Marine Sanctuary) were sampled during spring 2016 to determine whether Winter Flounder are spawning in non-coastal, deep waters in the southern GOM. In total, 1,384 Winter Flounder were caught by trawl, measured, sexed, and assessed for reproductive stage during the peak spawning season (March–May). These fish showed clear signs that spawning was occurring either at or very near to all three sites surveyed. In all sites, a shift from prespawn to postspawn females occurred. Running ripe females were caught at both Jeffreys Ledge and Stellwagen Bank on multiple occasions, and ripe and recently spawned females were caught at Bigear. Given that these sites are over 15 km from the coast, it is not energetically likely that fish in such advanced ...

Carcinus maenas (Linnaeus, 1758) in two New Hampshire estuaries. Part 2: assessment of average intermolt period

Green crabs, Carcinus maenas (Linnaeus, 1758), were sampled from two New Hampshire estuaries, Hampton-Seabrook Estuary (HSE) and Great Bay Estuary (GBE), over the course of a one year field season (Nov. 2009-Oct. 2010) in order to determine the timing of molt cycles and egg-bearing periods expressed by both populations. Average timing of population molt was assessed by length of average intermolt period, which was estimated based on the color of the ventral side of the crab using the Munsell paint color charts, 40 hue edn. Crabs in both estuaries appeared to be on a simultaneous molting schedule centered around the month of June. Females experienced a single population-wide molt beginning in June and completed by November. Males experienced two population-wide molts starting in April and November that were both completed by June. Regressions between color variables and crab size or distance from the mouth of the estuary ( α = 0 . 05 ) revealed no statistically significant correlations. Photoperiod (day-length) appeared to be the most important environmental cue for green crab molting and reproduction. Berried females were captured from January until November, with peak catch occurring in May. These results suggest that green crabs in both estuaries experience a single summer breeding season between June and November, which coincides with a period of relatively lower foraging activity as compared to the spring and fall months.

12th Flatfish Biology Conference 2010 program and abstracts, December 1-2, 2010, Water's Edge Resort and Spa, Westbrook, CT

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