DOI: 10.6075/j0bp02xc
title: Data from: Length-weight relationships for 18 coral reef fish species from the central Pacific. In Fish Length-Weight Parameters

description: Data analysis was done using R statistical software.
description: Fish were collected during multiple expeditions to the NLI from 2006-2011 using a variety of methods including hand nets, 3-prong spears, spearguns, handlines, fishing poles, and fish anesthetic (see Supplemental Table 1 for expedition details). Total length (TL) and weight were taken immediately after collection when possible, but in some cases field conditions (e.g., ship-based operations preventing collection of reliable weight estimates) required that specimens be frozen and brought to the laboratory for analysis. To account for the potential effects of freezing on fish body weight, we compared the fresh weight to thawed weight across taxa for specimens that had both measurements (Ajah & Nunoo, 2003; Florin & Lingman, 2008; Hay, 1984; Ogle, 2009). Changes in fish weight (g) were expressed in terms of percent weight loss for each specimen and mean percent was calculated for each species. Due to high surface-to-volume ratios, smaller fishes lost a greater proportion of weight during the freezing process. The change in weight (WFresh - WFrozen) was log-transformed and plotted against the log-transformed frozen weight, resulting in a robust linear model. All assumptions of linear regression were met. The intercept (α1) and slope (α2) were estimated for each species based on the following equation:

ln(ΔW) = ln(α1) + α2ln(WFrozen), 

supporting a power function,

ΔW = α1WFrozenα2, 

where ΔW is the change in weight of the fish (g) and WFrozen is the frozen weight (g) of the fish. Since no appreciable differences in parameter estimates were observed across species of differing body sizes, we re-ran the model incorporating all of the fish species and calculated a mean estimate to be used as the conversion factor for all species across all body weights. The conversion factors were estimated as: α1 = 0.0946 (SE 0.0063), α2 = 0.5620 (SE 0.0147), and the coefficient of determination was r2 = 0.705. Thus, fishes collected for this study that lacked initial weights from the field could have their frozen weights converted to initial ‘fresh’ weights using the following equation:

WFresh = WFrozen + α1WFrozenα2.
description: These data were used to generate the length-weight relationships (LWR) for 18 species of coral reef fish from the northern Line Islands, a geographically remote area of the central Pacific (3.48° N 158.80° W). Specimens were collected across multiple field campaigns (on average: 3-5 days per island, 2 islands per year) from 2006 to 2011 using 3-prong spears, spearguns, handlines, fishing poles, and fish anesthetic with hand nets (1 mm mesh), and measurements of total length (TL – 0.1 cm precision) and total weight (W – 0.01 g precision) were taken. The LWR were calculated using the linear regression of the log-transformed length and weight data. New LWR are reported for 13 common species from the central tropical Pacific, as well as LWR across new maximum total lengths for five species, thus expanding the observed size range for these scaling relationships.