Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

Abstract

SynopsisWe compare the biology of the tropical species Sillago analis and the temperate species Sillago schomburgkii in Shark Bay, a large subtropical marine embayment on the west coast of Australia. This environment constitutes the approximate southernmost and northernmost limits of the distributions of these two species, respectively. The annuli visible in sectioned otoliths of S. analis and S. schomburgkii were shown to be formed annually. Their numbers were thus used to age the individuals of these two species, which are morphologically very similar and live in the same habitats. Although the growth rates of S. analis and S. schomburgkii are very similar until maturity is attained, they subsequently diverge, with S. schomburgkii investing relatively more energy into somatic growth. The maximum total lengths and ages of both the females (320 mm, 6 years) and males (283 mm, 8 years) of S. analis were not as great as those of the females (383 mm, 9 years) and males (302 mm, 9 years) of S. schomburgkii. In Shark Bay, S. schomburgkii spawns earlier and longer than S. analis, i.e. August to December vs January to March, which would result in the juveniles of these two species recruiting into nursery areas at different times. In addition, S. schomburgkii spawns earlier and for longer in Shark Bay than in temperate marine waters ~ 800 km further south, presumably reflecting an earlier attainment in that subtropical embayment of the range of water temperatures over which this species typically spawns. However, although environmental conditions in Shark Bay and those temperate marine waters differ markedly, the growth of the corresponding sexes of S. schomburgkii in these two water bodies is similar.3

Reproduction, age and growth ofSillago maculatain south-eastern Australia

“…Female S. maculata grew faster and attained a larger maximum length than males, a common pattern observed among other sillaginids, including S. aeolus (Rahman and Tachihara, 2005b), S. analis (Coulson et al., 2005), S. punctata (Hyndes et al., 1998) and S. schomburgkii (Coulson et al., 2005).…”

“…Thirteen species occur in Australian waters, and aspects of the biology and ecology of several species have been investigated. This is particularly true for coastal species in western and southern Australia (Hyndes and Potter, 1996, 1997; Hyndes et al., 1998; Fowler et al., 2000; Coulson et al., 2005). In contrast, little biological information exists for estuarine and coastal species in south‐eastern Australia (but see Burchmore et al., 1988), even though several species are important in commercial and recreational fisheries (McKay, 1992; Kailola et al., 1993).…”

The life‐history ofCheilodactylus rubrolabiatusfrom south‐western Australia and comparison of biological characteristics of the Cheilodactylidae and Latridae: support for an amalgamation of families

“…The difference in the L T at age of females on the two coasts, however, as determined from their von Bertalanffy growth equations, was ≤5% between ages 1 and 10 years, where most of the data lay. As these differences are small and growth curves will almost inevitably tend to differ significantly when based on large sample sizes (Cerrato, ), the differences are assumed, as in comparable cases (Coulson et al, , , ), to be of little or no biological significance. Thus, the L T at age for the corresponding sexes on the two coasts were combined to derive single growth curves for each sex (Figure ).…”

“…A likelihood‐ratio test was used to determine whether the L T 50 for female C. rubrolabiatus exceeded that of males on each coast, assuming a common value of for each sex and whether the L T 50 for females or males on the south coast exceeded that of the corresponding sex on the lower west coast, assuming a common value of for each coast (Coulson et al, , ).…”

Depth interactions and reproductive ecology of sympatric Sillaginidae: Sillago robusta and S. flindersi

“…burrus, S. vittata, S. robusta, S. schomburgkii and S. bassensis off western Australia (Coulson et al 2005, Hyndes & Potter 1996, Hyndes et al 1996a,b, 1997. Similarly, the demographic characteristics of the estuarine-nearshore distributed S. ciliata, S. maculata and S. analis have been examined in eastern Australia (Cleland 1947, Burchmore et al 1988, Kendall & Gray 2009, Stocks et al 2011.…”