CORE Metadata, citation and similar papers at core.ac.uk Provided by Research Repository MURDOCH RESEARCH REPOSITORY This is the author’s final version of the work, as accepted for publication following peer review but without the publisher’s layout or pagination. The definitive version is available at http://dx.doi.org/10.1016/j.fishres.2011.04.021 Beatty, S., de Graaf, M., Molony, B., Nguyen, V. and Pollock, K.H. (2011) Plasticity in population biology of Cherax cainii (Decapoda: Parastacidae) inhabiting lentic and lotic environments in south-western Australia: Implications for the sustainable management of the recreational fishery. Fisheries Research, 110 (2). pp. 312-324. http://researchrepository.murdoch.edu.au/4693/ Copyright: © 2011 Elsevier B.V. It is posted here for your personal use. No further distribution is permitted. Accepted Manuscript Title: Plasticity in population biology of Cherax cainii (Decapoda: Parastacidae) inhabiting lentic and lotic environments in south-western Australia: implications for the sustainable management of the recreational fishery Authors: Stephen Beatty, Martin de Graaf, Brett Molony, Vinh Nguyen, Kenneth Pollock PII: S0165-7836(11)00170-6 DOI: doi:10.1016/j.fishres.2011.04.021 Reference: FISH 3218 To appear in: Fisheries Research Received date: 9-11-2010 Revised date: 29-4-2011 Accepted date: 30-4-2011 Please cite this article as: Beatty, S., de Graaf, M., Molony, B., Nguyen, V., Pollock, K., Plasticity in population biology of Cherax cainii (Decapoda: Parastacidae) inhabiting lentic and lotic environments in south-western Australia: implications for the sustainable management of the recreational fishery, Fisheries Research (2010), doi:10.1016/j.fishres.2011.04.021 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. *Highlights The study demonstrates considerable variability in the population biology of a large parastacid. Growth rate and productivity of adult Cherax cainii was greater in the lotic system. Stunting of adults occurred in the habitat limited lentic population and the stock was over exploited. Sustainable increases in fishing exploitation may be possible in more pristine rivers. Habitat and water quality decline and rainfall reductions are the major long-term threats to the fishery. Accepted Manuscript Page 1 of 44 *Manuscript including abstract 1 Plasticity in population biology of Cherax cainii (Decapoda: Parastacidae) 2 inhabiting lentic and lotic environments in south-western Australia: 3 implications for the sustainable management of the recreational fishery 4 5 Stephen Beattya,*, Martin de Graafbc, Brett Molonyb, Vinh Nguyenb, Kenneth Pollocka,b 6 7 a*Freshwater Fish Group and Fish Health Unit, Centre for Fish and Fisheries Research, Murdoch 8 University, 90 South St, Murdoch, Western Australia, 6150, Australia 9 bWestern Australian Fisheries and Marine Research Laboratories, Department of Fisheries, 10 Government of Western Australia, PO Box 20 North Beach, Western Australia, 6920, Australia 11 cCurrent address: IMARES Wageningen UR, PO Box 68, 1970 AB IJmuiden, The Netherlands 12 *Corresponding author. Tel.: +61 893602813; fax: +61 893607512. E-mail address: 13 [email protected] (S. Beatty) 14 15 Accepted Manuscript 1 Page 2 of 44 16 Abstract 17 The Smooth Marron Cherax cainii is endemic to south-western Australia and supports an iconic 18 recreational fishery that exploits stocks in both lentic and lotic systems. This study is the first to 19 determine and compare the population biology of a parastacid from both lentic and lotic systems 20 and aimed to gather the information necessary for more effective management of the fishery. 21 Modal progression demonstrated growth rates of juvenile C. cainii were greater in the lentic 22 (Wellington Dam) compared to the lotic (Warren River) system, however, mark-recapture 23 suggested the growth rate of the adult component of the lentic population was stunted whereas in 24 the lotic population 60-90 mm OCL individuals were common and had a faster growth rate. The 25 Wellington Dam stock appeared to be over-exploited and had very low productivity whereas the 26 Warren River stock had relatively low fishing exploitation and a high productivity resulting from 27 higher growth rates coupled with higher population densities (with the trappable population sizes 28 estimated using the open POPAN formulation in the MARK software program). Comparisons of 29 these biological parameters were made with populations elsewhere and there existed a considerable 30 plasticity that is probably due to differences in thermal regimes, degree of habitat complexity, food 31 resource availability and fisher accessibility. The findings demonstrate the need to determine the 32 level of intraspecific biological plasticity in freshwater crayfish in order to sustainably manage their 33 fisheries. 34 35 KEYWORDS: freshwater crayfish, biological plasticity, aquatic habitat, sustainable exploitation, 36 mark-recapture methods, estimation of demographic parameters. 37 Accepted Manuscript 2 Page 3 of 44 38 1. Introduction 39 The South West Coast Drainage Division of Australia is recognised as a global biodiversity 40 hotspot due to an exceptional concentration of endemic species undergoing a major loss of habitat 41 (Myers et al., 2000). This is reflected in the high degree of endemism of the freshwater fauna in the 42 region with 80% of native freshwater fish (Morgan et al., 1998; Allen et al., 2002) and 100% of 43 native freshwater crayfish (Austin and Knott, 1996; Crandall et al., 1999; Austin and Ryan, 2002) 44 being endemic to the region. The region’s aquatic ecosystems have been severely impacted by 45 habitat alterations, particularly secondary salinisation (Halse et al., 2003; Morgan et al., 2003; 46 Beatty et al., 2011), introduced aquatic fishes (Morgan et al., 2002, 2004; Tay et al., 2007) and an 47 eastern Australian freshwater crayfish (Beatty et al., 2005a; Beatty, 2006). 48 The ecosystems of south-western Australia are naturally low in productivity with allochthonous 49 material generally the dominant source of energy (Bunn and Davies, 1990). This low productivity 50 results in the region’s freshwater fishes being relatively small in size (generally <200 mm total 51 length (TL)) and of little value for recreational or commercial fisheries (Morgan et al., 1998; Allen 52 et al., 2002). However, the freshwater crayfish fauna of the region includes the third largest species 53 in the world, the Smooth Marron Cherax cainii Austin and Ryan, 2002. Cherax cainii supports a 54 relatively small (7,400 fishers, 20.8 tonnes of catch in 2007) yet iconic recreational fishery in both 55 lotic (that receive ~70% of the annual effort in terms of total number days fished) and artificial 56 lentic (~30% of annual effort) systems (Molony et al., 2002; de Graaf and Barharthah, 2008). 57 Freshwater crayfishes are known to exhibit considerable plasticity in biological and ecological 58 traits (e.g. Honan and Mitchell, 1995; Payne, 1996; Hayes et al., 2009). This plasticity has been 59 attributed to geneticAccepted (Austin, 1998; Vogt et al., 2008 ) orManuscript environmental (Parkyn et al., 2002; Beatty 60 et al., 2005b) variability as well as the presence of introduced species (Larson and Magoulick, 2008; 61 Hayes et al., 2009). In particular, the major environmental differences that exist between reservoirs 62 and rivers (Bunn and Arthington, 2002; Arthington et al., 2010; Olden and Naiman, 2010) are 63 known to cause variability in population biology parameters of aquatic species (e.g. Parker et al., 64 1995). For example, warmer environments and/or systems with greater productivity may increase 3 Page 4 of 44 65 growth rates and lengths at first maturity of freshwater crayfishes (Parkyn et al., 2002; Beatty et al., 66 2005b). Quantification of the biological plasticity of Southern Hemisphere parastacids is relatively 67 limited (Honan and Mitchell, 1995; Austin, 1998; Beatty et al., 2003a, 2005b; Jones et al. 2007), 68 which is somewhat surprising given that there are at least 140 species recognised in Australia alone 69 and a number of them support recreational and commercial fisheries and/or aquaculture industries 70 (Crandall et al., 1999). 71 Aside from two studies in the 1970s (see Morrissy, 1970, 1975), it is only recently that the 72 population and reproductive biology of C. cainii has been determined from wild aquatic systems 73 (Beatty et al., 2003a, 2005b). Those studies found that considerable differences existed between 74 populations for several biological parameters and suggested that this species may have a variable 75 life history (Morrissy, 1975; Beatty et al., 2003a, 2005b). Despite this apparent high variability, 76 comprehensive evaluation of key population biology parameters such as growth, mortality, 77 exploitation rates, abundance, density and productivity of populations have not yet been 78 determined; and are urgently required to ensure the ongoing sustainable management and 79 monitoring of the fishery (Beatty et al., 2005b). 80 The annual landings and catch per unit effort (CPUE, number of marron per fisher per day)