Butcher P.A.,University of New England of Australia |
Butcher P.A.,Australian Department of Primary Industries and Fisheries |
Boulton A.J.,University of New England of Australia |
Macbeth W.G.,Cardno Ecology Laboratory |
Malcolm H.A.,Australian Department of Primary Industries and Fisheries
Marine Ecology Progress Series | Year: 2014
Multiple-use marine parks are a powerful management tool to help protect marine biodiversity and sustain wild fisheries while allowing some access to recreational and commercial activities using zoning arrangements. Research has focused on fish but far less is known about the effectiveness of zoning for other groups, such as exploited crustaceans, especially in estuaries. In this 8 yr study, we tested the hypotheses that unfished zones, which had been closed to fishing since 1991, would have higher abundances (catch per unit effort) of the giant mud crab Scylla serrata in 3 estuaries (Wooli, Corindi and Sandon) of the Solitary Islands Marine Park (SIMP) in New South Wales, Australia, and that recovery after fishing closure would be rapid. Replicate fished and unfished zones were sampled from December 1998 (Wooli) and July 2000 (Corindi and Sandon) until April 2007. In August 2002, re-zoning occurred with some estuarine sections reopened to trapping, some newly closed and others either remaining closed or open. This enabled Before-After-Control-Impact analyses to test our hypotheses. Crab numbers increased rapidly after zone closure and unfished zones protected giant mud crabs from exploitation with catches 2 to 3 times greater than in fished zones. Although there was substantial temporal variation in crab abundance within and among the 3 estuaries, responses to zoning were consistent and spatial protection in estuaries in the SIMP proved effective for sustaining giant mud crab populations. This type of management shows promise for protecting or replenishing stocks of other species of crabs worldwide. © Inter-Research 2014.
Gridley T.,University of St. Andrews |
Gridley T.,University of Pretoria |
Cockcroft V.G.,Nelson Mandela Metropolitan University |
Hawkins E.R.,Southern Cross University of Australia |
And 3 more authors.
Marine Mammal Science | Year: 2014
Common bottlenose dolphins (Tursiops truncatus) use individually distinctive signature whistles which are highly stereotyped and function as contact calls. Here we investigate whether Indo-Pacific bottlenose dolphins (T. aduncus) use signature whistles. The frequency trace of whistle contours recorded from three genetically distinct free-ranging populations was extracted and sorted into whistle types of similar shape using automated categorization. A signature whistle identification method based on the temporal patterns in signature whistle sequences of T. truncatus was used to identify signature whistle types (SWTs). We then compared the degree of variability in SWTs for several whistle parameters to determine which parameters are likely to encode identity information. Additional recordings from two temporarily isolated T. aduncus made during natural entrapment events in 2008 and 2009 were analyzed for the occurrence of SWTs. All populations were found to produce SWTs; 34 SWTs were identified from recordings of free-ranging T. aduncus and one SWT was prevalent in each recording of the two temporarily isolated individuals. Of the parameters considered, mean frequency and maximum frequency were the least variable and therefore most likely to reflect identity information encoded in frequency modulation patterns. Our results suggest that signature whistles are commonly used by T. aduncus. © 2013 Society for Marine Mammalogy.
Hawes I.,Worldfish Center |
Hawes I.,University of Canterbury |
Lasiak T.,Cardno Ecology Laboratory |
Smith M.L.,Cardno Ecology Laboratory |
Oengpepa C.,Worldfish Center
Journal of Shellfish Research | Year: 2011
In the Solomon Islands, there have been three periods of commercial exploitation of the silver (gold)-lip pearl oyster Pinctada maxima. The most recent ended in 1993, when export of all species of pearl oysters was banned to allow stocks to recover from overexploitation. In 2007, a nationwide survey was undertaken to determine the status of the population. Communities adjacent to former fishing grounds were interviewed about past and current fishing practices, and the abundance, size composition, and quality of P. maxima shells were assessed by drift diving. In total, 117 P. maxima were recorded, from 33 of 96 transects. When present, the mean density of oysters varied from less than 0.101.23 oysters/400-m 2 transect. Size structure was biased toward large individuals, with mean and median shell size for all oysters taken being 219 mm. There appears to have been little or no recovery of P. maxima stocks since their export was banned. The existence of small populations of large individuals implies persistent failure of reproduction, spat settlement, and/or recruitment during the past decade. Exploitation may have reduced the P. maxima populations to such an extent that their fertilization success has become susceptible to Allee effects. Recent poaching of shell reported by local villagers may have compounded slow or sporadic recruitment. If the stocks do eventually recover, management strategies that protect the recovered population will need to be implemented to prevent a repeat of the overfishing seen in previous harvest cycles.
Schlacher T.A.,University of The Sunshine Coast |
Noriega R.,Griffith University |
Jones A.,South Australian Museum |
Dye T.,Cardno Ecology Laboratory
Science of the Total Environment | Year: 2012
Beach erosion is likely to accelerate, driven by predicted consequences of climate change and coastal development. Erosion is increasingly combated by beach nourishment, adding sand to eroding shores. Because a range of engineering techniques exists to nourish beaches, and because these techniques differ in their environmental effects, assessments of ecological impacts need to be tailored and specific. Here we report on impacts and recovery of benthic invertebrates impacted by beach nourishment operations undertaken at Palm Beach (SE Queensland, Australia). Assessments are made based on a beyond-BACI design, where samples were taken once before nourishment and twice afterwards at the impact and two control sites. Because almost all of the sand was deposited on the upper beach and later moved with bulldozers down-shore, we specifically examined whether the effects of nourishment varied at different heights of the beach-a little-studied question which has management implications. Impacts on the fauna were massive on the upper and middle levels of the beach: samples collected two days after the conclusion of nourishment were entirely devoid of all invertebrate life ('azoic'), whereas weaker effects of nourishment were detectable on the lower shore. Recovery after five months also varied between shore levels. The sediment of the upper level near the dunes remained azoic, the fauna of the middle shore had recovered partially, and the lower level had recovered in most respects. These findings indicate that the height and position of sand placement are important. For example, rather than depositing fill sand on the intertidal beach, it could be placed in the shallow subtidal zone, followed by slow up-shore accretion driven by hydrodynamic forces. Alternatively, techniques that spread the fill sand in thin layers (to minimize mortality by burial) and leave unfilled intertidal refuge islands (to provide colonists) may minimize the ecological impacts of beach nourishment. © 2012.