Spatial and temporal variability in the condition of postlarval and juvenile Penaeus plebejus sampled from a population subjected to pilot releases

Abstract

The potential for hatchery-release programs to augment the harvest rates of fisheries can be limited by environmental factors associated with survival, growth and body condition among released individuals. We assessed spatial and temporal variability in the condition of postlarval and small juvenile (1-10 mm carapace length) eastern king prawns Penaeus plebejus Hess sampled from an estuarine population subjected to pilot releases of 3 million postlarvae per year in southeastern Australia. Variability in the length-weight relationship was used as a measure of condition and compared between (1) autumn/winter and spring/summer periods and (2) bare and macrophytic habitats for P. plebejus sampled from a population in a closed estuarine system. At a reference carapace length of 3.97 mm, condition was ~14% higher for individuals sampled from bare habitat and ~16% higher for those sampled during autumn/winter compared, respectively, with individuals sampled within macrophytic habitat and during spring/summer. Further experimental work on the factors investigated here is encouraged to increase our understanding of the environmental characteristics and mechanisms that lead to improved condition and thus persistence of stocked populations of P. plebejus. KEY WORDS: Stock enhancement · Fisheries management · Habitat · Season · Prawns · Penaeid · ICOLL Resale or republication not permitted without written consent of the publisherAquacult Environ Interact 2: [15][16][17][18][19][20][21][22][23][24][25] 2011 Although there are examples of successful stock enhancement programs (e.g. Leber & Arce 1996, McEachron et al. 1998, Zeimann 2003, some have been shown to impact negatively on receiving communities (e.g. Hilborn & Eggers 2000, Araki & Schmid 2010 and many have been considered economic failures because of poor longevity of enhanced populations and a consequent inability to supplement ex ploited populations (Blankenship & Leber 1995, Bell et al. 2005. For example, analysis of catch-and-release histories for Penaeus japonicus in Japan suggested that hatchery releases did not succeed in augmenting total production of this species (Hamasaki & Kitada 2006). In another instance, analysis of fishermen's log books following the release of postlarval and juvenile Homarus gammarus failed to show any evidence of successful enhancement of the species' stocks (Addison & Bannister 1994).The short-lived nature of many enhanced populations is often attributed to a poor understanding of the spatial and temporal environmental factors associated with maximum survival, growth and body condition among released individuals (Crowl et al. 1992, Einum & Fleming 2001. This has resulted in the indis cri mi nate release of many species into habitats and ecosystems that do not complement their seasonal and spatial requirements across critical life history stages (Leber 2002). Investigations of the most appropriate release strategies and long-term monitoring programs can significantly improve the success of stock enhancement efforts by def...

Competition between wild and captive-bred Penaeus plebejus and implications for stock enhancement

“…A number of natural factors that show greater variability in wild conditions could affect the way wild and captive-bred Penaeus plebejus respond to decreasing levels of food and shelter. In water temperatures that are higher than the temperatures recorded in the current study, for example, greater consumption rates due to higher metabolic requirements for juvenile P. plebejus (Haywood & Staples 1993, Ochwada-Doyle et al 2011) may increase competition for food between the 2 categories. Future experiments conducted at broader spatiotemporal scales and in a range of environmental conditions are needed to test the generality of the findings reported here and therefore assist in developing a more general model for intra-specific competition among P. plebejus in stocked systems.…”

A tool for tracking genetic contributions of wild Penaeus (Melicertus) plebejus broodstock to hatchery populations

“…PL were ongrown for an additional 15 days, after which they had reached a suitable size for release (Ochwada‐Doyle et al . ). Random PL samples were collected from each rearing tank and immediately preserved in 95% ethanol for genetic analysis.…”

Response of estuarine consumer communities following the stocking of a juvenile penaeid (Penaeus plebejus) over two consecutive years

“…Penaeid prawns have been a focus of research efforts and are considered to be good candidates for stock enhancement programmes (Bell et al., ; Loneragan et al., ). In open systems, modelling work has focused on Penaeus esculentus Haswell (Loneragan, Ye, Kenyon & Haywood, ; Ye, Loneragan, Die, Watson & Harch, ) while in estuaries, more targeted work has been conducted on species such as Penaeus plebejus (Hess) (Ochwada‐Doyle, Gray, Loneragan, Suthers & Taylor, ; Ochwada‐Doyle, Gray, Longeragan, Taylor & Suthers, ) and Metapenaeus dalli Racak (Broadley, Tweedley & Loneragan, ). A feature of many estuaries in southern Australia is limited connectivity with the marine environment.…”

“…Penaeus plebejus (hereafter referred to as eastern king prawn) is a popular and valuable species in Australia that supports a niche recreational fishery in shallow estuaries in south‐eastern Australia (Reid & Montgomery, ). Following extensive research (Ochwada‐Doyle, Loneragan, Gray & Taylor, ; Ochwada‐Doyle et al., ; Taylor & Ko, ) and environmental assessments (Blount et al., ), an ongoing programme releasing post‐larval eastern king prawn into estuarine lagoons commenced in 2014, to enhance the local recreational harvest in recruitment limited estuaries (as opposed to rebuilding spawning stock). Following recruitment to estuaries as post‐larvae, eastern king prawn spend a number of months within estuaries before adolescent prawns emigrate to the ocean and commence a northward migration towards spawning grounds (Montgomery, ).…”