Bay anchovy Anchoa mitchilli production and consumption in mid-Chesapeake Bay based on a bioenergetics model and acoustic measures of fish abundance

Abstract

A growth model of bay anchovy Anchoa mitchilli was developed based on weight and temperature-specific physiological data taken from laboratory and field experiments. The model was adjusted for Chesapeake Bay (USA) conditions to estimate bay anchovy population production and consumption as a function of bay anchovy hatch date, annual mortality, and acoustic measures of fish abundance. Spatially explicit models of bay anchovy consumption were developed to demonstrate how changes in spatial patterning and absolute scaling of the biological and physical environment might affect prey consumption in May and July. In model simulations, bay anchovy grew 3 to 6 % d-' during summer and fall, and young-of-the-year ( Y O Y ) bay anchovy biomass peaked in November (16270 kg km-'). Weight-specific consumption rate of juvenile bay anchovy was about 60 % d'' during summer, and population consumption peaked in September (3350 kg km-' d-l). Population production rate of YOY also peaked in September at 290 kg d-', and annual production was 30770 kg km-' If all mortality was due to predation, bay anchovy could provide 133 kg food km-' d-' for piscivores in November, which could support the maximum daily consumption of 13 300 age-2 striped bass Morone saxatilis per km2. The average trophic efficiency of bay anchovy was 10.7 % with a large seasonal variation (0 to 18 %). Sensitivity analyses identified that weight and temperature-specific consumption and respiration parameters were most sensitive in model simulations of fish growth. Compared with the estimated zooplankton production, the average bay anchovy consumption only accounted for a small portion of daily zooplankton production But our spatially-explicit model indicated that local depletions of zooplankton were possible due to spatial patchiness of predator and habitat heterogeneity, particularly in July.

Estimating fish production potentials using a temporally explicit model

“…Seasonal fluctuations of GRP, as observed in this study, have been reported elsewhere (Mason et al, 1995;Brandt and Kirsch, 1993;Goyke and Brandt, 1993;Luo and Brandt, 1993). Using a spatially explicit approach, Goyke and Brandt (1993) demonstrated seasonal fluctuations in chinook GRP measured along a cross-lake transect of Lake Ontario during 1991-1992.…”

“…Spatial models have demonstrated that predators tracking both prey abundances and optimal temperatures have highest production potentials in areas where these environmental characteristics overlap (Brandt et al, 1992;Brandt, 1993;Luo and Brandt, 1993;Goyke and Brandt, 1993;Hondorp and Brandt, 1996). Spatial modelling, however, is largely limited to 'snapshots' taken over short time periods, and does little to resolve how often these overlapping conditions develop and how long they persist.…”

A coupled plankton–anchovy population dynamics model assessing nonlinear controls of anchovy and gelatinous biomass in the Black Sea

“…Mathematical formulation of the weight growth model: The bioenergetics-based anchovy weight growth model follows Luo & Brandt (1993), Rose et al (1999), McDermot & Rose (2000), and Megrey et al (2007). No weight growth occurs in egg and yolk-sac larval phases of each daily cohort.…”

“…Respiration involves the sum of routine and active metabolic losses, expressed by Luo & Brandt (1993) as (6) where r 1 (mg C d -1 ) denotes the maximum rate of routine respiration at optimal temperature (Table 6), r 2 is the exponent of weight dependence of respiration (Table 6), ƒ(T) is the overall temperature limitation function for the euphotic zone (Eq. 5d), and A F is a constant anchovy activity factor (Table 5).…”

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“…It becomes sub-optimal at higher temperatures because there is evidence that larval growth slows down when temperatures exceed 25°C (Chiu and Chen, 2001), which was observed in surface waters of the Black Sea during anomalously warm years such as in the late summer of 2001. Such a decrease in growth rate at high temperatures has also been used in anchovy models for other regions such as the Chesapeake Bay (Luo and Brandt, 1993;Rose et al, 1999).…”