Rapid reproductive analysis and length–weight relations for five species of coral-reef fishes (Actinopterygii) from Papua New Guinea: Nemipterus isacanthus, Parupeneus barberinus, Kyphosus cinerascens, Ctenochaetus striatus (Perciformes), and Balistapus undulatus (Tetraodontiformes)

Abstract

T. 2017. Rapid reproductive analysis and length-weight relations for five species of coral-reef fishes (Actinopterygii) from Papua New Guinea: Nemipterus isacanthus, Parupeneus barberinus, Kyphosus cinerascens, Ctenochaetus striatus (Perciformes), and Balistapus undulatus (Tetraodontiformes). Acta Ichthyol. Piscat. 47 (2): 107-124.Background. We present length-weight relations (LWR) and describe the reproductive biology of five species of coral reef fishes from Papua New Guinea (PNG). Each of these species are targeted by artisanal-and smallscale commercial fisheries throughout the country. As such the purpose of this study was to provide baseline reproductive information that can be used for future evaluation and management of the fishery. Materials and methods. We used recently developed methods for rapid, low-cost, on-site, histology-based reproductive analysis that requires minimal research infrastructure. These methods use standard techniques (e.g., plastic embedding) that have been modified such that work can be conducted in remote field settings without electrical service. We studied the following fish species: the teardrop threadfin bream, Nemipterus isacanthus (Bleeker, 1873); the dash-and-dot goatfish, Parupeneus barberinus (Lacepède, 1801); the blue sea chub, Kyphosus cinerascens (Forsskål, 1775); the striated surgeonfish, Ctenochaetus striatus (Quoy et Gaimard, 1825); and the orange-lined triggerfish, Balistapus undulatus (Park, 1797). Results. In all species, length was an approximately cubic function of weight. Female B. undulatus mature at a smaller size than males; in the other four species males mature at a smaller size. Nemipterus isacanthus, K. cinerascens, C. striatus, and B. undulatus are gonochores. Females are rare or absent in the largest size classes of N. isacanthus, P. barberinus, C. striatus, and B. undulatus. For P. barberinus and B. undulatus, size classes well below maximum observed size are responsible for the majority of egg production. Conclusion. Our results differed markedly from those of macroscopic and data-deficient approaches and may help to avoid unnecessary management actions. Further, an emergent pattern challenges a current paradigm in reef-fish conservation and management; contrary to a general assumption for many reef-fish species, the largest ACTA ICHTHYOLOGICA ET PISCATORIA (2017) 47 (2): 107-124

Rapid reproductive analysis and weight-length relation of the humpnose big-eye bream, Monotaxis grandoculis (Actinopterygii: Perciformes: Lethrinidae), from Micronesia with implications for fisheries

“…The size-specific sex ratios reported here, where females become increasingly rare, or absent, with increasing length, are commonly reported for lethrinids (Ebisawa 1997, 2006, Trianni 2011, Currey et al 2013. However, the impact of this pattern on impressions of which size classes are responsible for the majority of populationlevel egg production is currently under-recognized (but see Longenecker et al 2014Longenecker et al , 2017. Failing to account for the negligible chance of large Monotaxis grandoculis individuals being female would lead to an overestimate of 93 136 eggs per spawning event of per capita egg production by the largest individuals in this population.…”

“…Rapid, histology-based methods from Longenecker et al (2017) were used to obtain lengths and weights, to describe the sexual pattern, and to estimate size-atmaturity, sex-ratios, and a length-batch fecundity relation. Briefly, for each specimen fork length (FL) was measured to the nearest mm, and whole body weight was estimated with a hanging spring-scale.…”

Highly diverse mesophotic reef fish communities in Raja Ampat, West Papua

“…Small-scale fisheries gears that reach MCEs require additional cost and effort compared to those used in the shallows (Wood et al 2006;Lindfield et al 2014). Yet, in some regions MCEs may support important fisheries-for example, in Papua New Guinea mesophotic species comprise large a proportion of some subsistence fish catches (Longenecker et al 2017(Longenecker et al , 2019. Testing potential MCE refuge effects is challenging, however, as fish abundance, biomass, and community composition transitions with depth (Thresher and Colin 1986;Brokovich et al 2008;Rocha et al 2018;Pinheiro et al 2019) and with benthic composition and structural complexity (Boland and Parrish 2005;Gratwicke and Speight 2005;Bridge et al 2012).…”

Many immature individuals and largest size classes lacked females for three coral reef fishes (Actinopterygii) in Fiji market surveys: Implications for fishery management

“…Temporal and geographic variability in life history parameters is known for several coral reef fish species (Gust 2004;DeMartini et al 2014). In addition, estimates of reproductive parameters should be obtained via histological examination, when possible, to minimize biases (Grandcourt et al 2006(Grandcourt et al , 2011Vitale et al 2006;Longenecker et al 2017). For example, empirical relations (Froese and Binohlan 2000) that underly the Fish-Base life history tool (Froese and Pauly 2019) increasingly overestimate female size at maturity as the maximum size of a species increases Longenecker et al 2017).…”

“…In addition, estimates of reproductive parameters should be obtained via histological examination, when possible, to minimize biases (Grandcourt et al 2006(Grandcourt et al , 2011Vitale et al 2006;Longenecker et al 2017). For example, empirical relations (Froese and Binohlan 2000) that underly the Fish-Base life history tool (Froese and Pauly 2019) increasingly overestimate female size at maturity as the maximum size of a species increases Longenecker et al 2017). Also, macroscopic evaluation of gonads results in misclassification of sex and/ or reproductive status of up to half of the inspected specimens (Longenecker et al 2013a(Longenecker et al , 2013b(Longenecker et al , 2020, with the misclassifications tending to overestimate the number of mature females (Longenecker et al 2013a(Longenecker et al , 2013b, underestimate female size at maturity (Grandcourt et al 2006(Grandcourt et al , 2011, and overestimate female spawning biomass (Vitale et al 2006).…”