Can backcalculation models unravel complex larval growth histories in a tropical freshwater fish?

Abstract

This experimental study compared the precision and accuracy of the biological intercept (BI), modified fry (MF) and time-varying growth (TVG) backcalculation models in estimating the early growth of the tropical freshwater purple-spotted gudgeon Mogurnda adspersa. Larvae were reared up to 41 days post hatching under two temperatures and four different feeding regimes. Food and temperature treatments induced complex growth profiles among fish, and although total length (LT ) and otolith radius were related under all conditions, some uncoupling was evident in the otolith-somatic-growth (OSG) relationship of fish subjected to periods of changing food availability. Furthermore, otolith growth was found to be significantly influenced by temperature, but not by food availability. Analysis of backcalculation residuals by linear mixed effects modelling revealed that BI and TVG were equally precise in predicting somatic growth, with the highest accuracy provided by TVG. The performance of all the three models declined as the OSG relationship weakened under low-food conditions, with maximum errors estimated to be 39, 60 and 36% of observed LT for the BI, MF and TVG models, respectively. The need for careful validation of backcalculation models is emphasized when examining fishes subjected to variable environmental conditions, and when exploring the differential influence of temperature and food on fish LT and otolith growth.

Effects of salinity on survival, daily food intake and growth of juvenile round goby Neogobius melanostomus (Pallas, 1814) from a brackish water system

“…Growth of fishes is linked to appropriate conditions of the inhabited environment in food availability and water temperature (Starrs et al., ) and salinity (Bœuf and Payan, ). In our experimental design the salinity level was the only difference among treatments, while food availability and temperature were held constant.…”

Maternally transmitted isotopes and their effects on larval fish: a validation of dual isotopic marks within a meta-analysis context

“…Larval growth rates were highly variable among individuals, with the largest larva being double the size of the smallest after 31 days. The average TL (11.68 mm) was less than that recorded in a previous study in which larvae were reared individually under variable food and temperature regimes (Starrs et al 2013). However, the range of growth rates observed in the two studies was comparable.…”

“…The larvae rearing system has been described previously (Starrs et al 2013) but was modified for the present study. Forty-eight clear plastic 5 L tubs were arranged in a row-column design on two racks (24 tubs per rack) in a light-and temperature-controlled room (13 h light : 11 h dark and 27.1 ± 0.5°C SE).…”

Effects of temperature and ration on the otolith-to-somatic size relationship in juvenile Chinook salmon (Oncorhynchus tshawytscha): a test of the direct proportionality assumption

“…In the present study, the hot (218C) water temperature treatment during summer surpassed the optimum temperature for growth even for the juvenile Chinook fed the high (exceeded satiation) ration, representing a plausible explanation for the uncoupling in the otolith size-to-FL relationship between the cool and hot temperature treatments. Food deprivation has been shown to influence the otolith-to-somatic size relationship in other fish as a result of continued otolith development during periods when somatic growth is halted (Baumann et al 2005;Starrs et al 2013). Although the effect of prolonged starvation on increment formation has not been examined in post-smolt juvenile Chinook salmon, Neilson and Geen (1985) showed that alevins and fry produced at least one otolith increment per day across multiple rations, indicating some level of endogenously driven daily incremental deposition of CaCO 3 .…”