Age and size compositions, habitats, growth and reproductive characteristics of a terapontid (Pelates octolineatus) in coastal waters

Abstract

This study of Pelates octolineatus is the first to use individually aged fish to describe the life cycle of a terapontid, a speciose and abundant Indo-West Pacific family. On the lower west Australian coast, this species uses dense seagrass as a nursery area and, after ~1 year of life when approaching 100 mm in total length (TL), moves into deeper waters over sparser seagrass where it matures at the end of its second year at ~140-170 mm. The maximum TL and age were 256 mm and 10 years. A modified von Bertalanffy curve, allowing for a linear increase in the growth coefficient with age, improved the fit to the lengths at age of older P. octolineatus. Growth was even better described by extending this model to allow for seasonality through incorporating a sine-based curve. This model described well the seasonality exhibited by modal progressions in monthly length-frequency distributions. Instantaneous growth rates, particularly of the youngest age classes, peaked in the warm, summer months and the amplitude of seasonal change in these rates declined with increasing age. Gonadal recrudescence occurred in early spring as temperature and day length increased and spawning peaked in late-spring to mid-summer when temperatures were approaching their maxima.

Biology of a marine estuarine-opportunist fish species in a microtidal estuary, including comparisons among decades and with coastal waters

“…. This net was the same as that used for sampling P. octolineatus concurrently in coastal marine embayments (Veale et al 2015). Both nets were deployed either from the bank and pulled on to the shore or from a boat further from the shore when nearshore waters were particularly shallow, i.e.…”

“…The total length (TL) and total mass (M) of each P. octolineatus were recorded to the nearest 1 mm and 0.01 g. As in the concurrent study of P. octolineatus in marine embayments (Veale et al 2015), the gonads of each P. octolineatus >100 mm TL, the length at which ovaries and testes typically become distinguishable, were assigned macroscopically to one of the following maturity stages, based on the criteria of Laevastu (1965): I, virgin; II, immature-resting; III, developing; IV, maturing; V-VI, pre-spawning-spawning; VII, spent; VIII, recovering spent. Five ovaries and five testes of P.…”

“…Furthermore, this species was the most abundant teleost found in seagrass meadows in a large subtropical embayment in the mid-west coast of Australia (Burkholder et al 2013). As with another terapontid, Amniataba caudivittata, on the lower-west coast of Australia (Wise et al 1994), the growth of P. octolineatus in coastal marine waters is highly seasonal (Veale et al 2015).…”

“…They typically become mature 1 year later. P. octolineatus is, however, a classic marine estuarine-opportunist because, like several other species on the same coast, substantial numbers of its juveniles also enter estuaries and remain there throughout the year (Potter et al 1983;Loneragan et al 1986;Veale et al 2015). In terms of habitat, it is particularly noteworthy that, during extensive sampling of habitats in nearshore waters on the lower west coast of Australia, 0+ P. octolineatuswas only found to be abundant in seagrass (Valesini et al 2004).…”

“…In coastal marine waters on the temperate and microtidal lower west coast of Australia, many western striped grunter (Pelates octolineatus) spend their first year of life in dense, nearshore seagrass meadows in embayments and then move out into deeper offshore waters where seagrass is less dense (Veale et al 2015). They typically become mature 1 year later.…”