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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Measuring angler attitudes toward the catch-related aspects of recreational fishing

Anderson, David K. 01 November 2005 (has links)
The primary purposes of this dissertation were understanding the nature of an attitudinal scale designed to measure the consumptive orientation of recreational anglers and filling a gap in the published literature regarding measurement using the scale. Consumptive orientation was defined as the attitude anglers hold towards catching fish, including catching something, retaining fish (as opposed to releasing), catching large fish (size), and catching large amounts of fish (numbers). In order to confirm these four attitudes are measured by the scale, a model was hypothesized and tested using a confirmatory factor analysis on a sample of male anglers in Texas. It was reasoned that a different subculture may interpret the attitudinal statements differently; thus, the structure of the scale was explored using women as a separate sample. Finally, an example of how the scale could be used was provided by examining differences between tournament and nontournament anglers?? attitudes towards the four constructs measured by the scale. Overall, results were varied with the hypothesized model used to confirm the scale. While results indicated dropping four of the sixteen statements would not result in a significant change in the structure of the scale, results also confirmed there were four distinct attitudes measured by the consumptive orientation scale. The use of the scale with the larger angling population was confirmed by finding the same structure using a sample of women anglers. Finally, the scale was shown to be useful for examining activity-specific differences in angling social worlds. Differences were detected between tournament and nontournament anglers on three of the four consumptive attitudes: ??catching numbers,?? ??catching large/trophy fish,?? and ??retaining fish.?? Differences found were related to the commitment level of tournament and nontournament anglers. Further analysis examined how avidity may have affected differences among angler groups. These differences further current knowledge about tournament anglers and their expectations for fishing experiences. Overall, results support the usefulness of the consumptive orientation scale as a survey tool for understanding recreational fishing clientele.
2

Modelling recreational angling demand in Sweden based on region-specific inclusive values

Gustafsson, Johan January 2017 (has links)
This thesis endeavours to model a trip demand function for recreationalangling in Sweden, including the individual expected per-trip utility of regionalattributes. The analysis is conducted with the use of a Random Utility Model (RUM)for the estimation of ‘site-specific’ utility, and a negative binomial logit model fortrip demand. The site quality variable is stated as expected catch-rates (CR) definedin terms of three different specifications: sample mean CR, individually perfectlyforesighted CR, and an econometrically predicted individual CR. Results indicatethat the econometrically estimated individual catch-rate specification performs wellas an explanatory variable both when modelling discrete site choice and trip demand,while the sample mean and perfectly foresighted CR specifications provide withunintuitive and insignificant parameter values. The inclusive value of the regionchosen by the angler, estimated with the RUM, was subsequently found to be asignificant predicting variable for the number of recreational angling trips conductedby Swedish anglers.
3

Using Style of Participation among Texas Inshore Fishing Guides to Understand Displacement Behavior due to Perceived Spotted Seatrout (Cynoscion nebulosus) Population Declines

Smith, William 2012 May 1900 (has links)
Characterization of distinct angler fishing styles (e.g., how, where, and with what) allows resource managers the ability to predict how perceived impacts or modifications to fisheries resources (i.e., decline of fish species population) may impact different user groups. Recreation specialization provides a useful framework for understanding participation diversity among recreationists in terms of unique styles of participation. Bryan suggested that within an activity distinct types of participants exist that demonstrate characteristic styles of participation. Fundamental to Bryan's development of specialization were contextual attributes that characterize participant engagement in a recreation activity. However, advancement in specialization has been accompanied by a departure from Bryan's original conceptualization describing activity context. I revisited how specialization is operationalized and developed a contextual style of participation typology and self-classification measure to investigate displacement and substitution behavior among Texas inshore fishing guides. Data were collected in two separate phases. In 2010, I conducted an exploratory investigation that included eighteen face-to-face, in-depth interviews with key informants spanning the entire coast. In 2011, I conducted a quantitative investigation that included mailing a 12 page self-administered survey to all Texas Parks and Wildlife licensed saltwater fishing guides (n=909). Thematic analysis drawing on grounded theory revealed that the salience of six contextual attributes (i.e., bait type, tackle type, fishing method, casting tactic, water depth, and fish species) that characterized four distinct styles of participation (e.g., Bait, All-purpose, Lure, and Sight-casting Guides). A unidimensional self-classification measure was developed based on my guide typology and discriminant analysis revealed it performed as well as a multidimensional measure of specialization. Ultimately, analysis of variance revealed significant differences existed among self-classification categories with respect to substitution behavior (e.g., targeting alternative species of fish, fishing in another location, and using alternative fishing methods or bait types) due to perceived spotted seatrout declines during 2010. In short, my findings suggest that anglers respond differently due to perceived spotted seatrout declines based on their preferred contextual style of participation. A contextual approach to understanding style of participation provides fisheries managers an effective method for understanding and mitigating social and ecological issues.
4

On the Feasibility of Marine Recreational Fishing¡VA Case Study for Hsiao-Liu-Chiu Island

Yang, Jian-de 18 August 2005 (has links)
This study focuses on the feasibilities of Marine Recreational Fishing at Hsiao- Liu-Chiu Island by presenting its resource distribution and discussing the current fishing business conditions around the island. The current situations of local re- creational fishing businesses are evaluated by SWOT analysis. Tourists who visit the island are surveyed as research subject. Through questionnaires and field recreation activity investigation, this study demonstrates various possible development of re- creational fishing. The conceptual framework of this study is based on a non- marketing method - Contingent Valuation Method (CVM) - to analyze collected data. The method has estimated the economical value of Hsiao-Liu-Chiu Island for future recreation activities with the willingness-to-pay (WTP) among the visiting tourists. A proper managerial and administrative system is also suggested in order to bring optimal performance in terms of economical value and resource application for the island's fishermen and tourists. According to the data collected: 70% of tourists are willingly to participate sport fishing; 90% would like to try recreational cage. And under CVM estimation, the WTP for sport fishing is about NT$896 per person, and NT$738 per person for recreational cage. Considering the total annual tourist population visiting Hsiao-Liu- Chiu Island, sport fishing may generates about NT$93,000,000 economical value annually, and about NT$98,000,000 for recreational cage. At the end, this research also provide suggestions on related management strategies and directions for the fishermen, cage owners, and local fishery organization
5

Assessing Morphometric and Otolith Measurements of Red Snapper, Lutjanus campechanus, to Characterize a Recreational Headboat Fishing in the Gulf of Mexico's Exclusive Economic Zone

Carrillo, Nicole Amber 02 October 2013 (has links)
As a highly targeted species, red snapper have been overfished since the 1970’s. Inadequate monitoring and reporting of discard rates impedes regulatory measures which are in place to allow red snapper populations to reach a healthy, sustainable level. This study documented the relationship between morphometric measurements and otolith analysis of red snapper caught from a recreational headboat fishing exclusively in the GOM’s EEZ of the upper Texas coast. The collected data of this research show that of the 594 red snapper caught within the sample group, 76% of the fish were discarded; analysis of the lengths of these discarded fish show that 15.5% were of regulation size (16 inches) or larger, clear evidence that high-grading is occurring. The effort for the total amount of red snapper caught by each individual angler within the sample group was measured to determine on average, approximately two red snapper were caught per person, per hour. The size distribution ranged from 16 to 32 inches with a mean total length of 21.32 inches for retained fish while discarded fish ranged from 5.5 to 22.5 inches with a mean of 14.23. Weight distribution ranged from 1.5 to 18.5 pounds with a mean of 5.81 pounds for retained fish and 0.20 to 6 pounds with a mean of 1.57 pounds for discarded fish. Age distribution ranged from 3 to 14 years of age; red snapper can live over 50 years, however relatively none (2.42%) older than 10 years were present in the sample, demonstrating a highly truncated population. Because fecundancy increases with age in females, longevity extends reproduction potential for red snapper. Management of reef fishes, and red snapper in particular, are difficult due to variances in growth rates and habitat use, complex population structure, and increasing reproduction levels with maturity. Recommendations for management include implementing an educational outreach program, reducing effort and discard rates, lowing rates of exploitation, and creating a marine reserve. Future research should address the entire Texas coast population of for-hire vessels (charter and headboats) to obtain data on discard rates and age distribution of red snapper.
6

From Substitution to Coping: Developing and Testing a Leisure Constraints-Based Coping Model

Tseng, Yung-Ping 14 January 2010 (has links)
The conceptualization of leisure constraints is dependent on negotiating a hierarchy of intrapersonal, interpersonal, and structural leisure constraints. It has become a recognizable and distinct subfield within leisure studies. Research has shown that the leisure constraints should not be necessarily viewed as insurmountable obstacles. Individuals can negotiate constraints by applying an array of coping mechanisms. Recently, Iwasaki and Schneider (2003) and Schneider and Stanis (2007) proposed that constraints negotiation and coping with stress share much in common. Leisure constraints are considered elements of stress, whereas constraint negotiation appears to share commonalities with ways of coping with stress. The distinction between negotiation and coping is that negotiation is something people have engaged in prior to participating in the activity, whereas coping involves strategies people more typically engage in during active participation (in response to unwanted or unanticipated situations). Based on past literature, I constructed a constraints-coping model to extend our understanding of constraints negotiation by integrating an understanding of coping mechanisms into leisure constraints-negotiation models. In order to broaden the scope of a constraints-coping framework, I integrated additional social indicators (e.g., commitment, motivation, place attachment, and frequency of participation) into my hypothesized model. First, my testing of the constraints-coping model provided empirical support for Iwasaki and his colleagues' suggestion that coping strategies can be potentially integrated into models of constraints-negotiation processes. Second, I confirmed that the three types of onsite constraints continue to have relevance for active participants. The three types of constraining factors directly influence subsequent aspects of leisure engagement for recreationists already participating. Third, I confirmed that recreationists are more likely to cope with constraints by employing an array of problem-focused coping strategies, rather than to simply adjust cognitively. However, my findings illustrate that recreationists' coping responses vary in response to different types of constraints encountered (e.g., intrapersonal, interpersonal, and structural). The experience of constraints did not universally result in the increased use of coping. Fourth, my results confirm that motivation is an immediate antecedent of constraints as well as a potential trigger for encouraging more problem-focused coping strategies. Last, four selected key variables (e.g., place attachment, commitment motivation, and frequency of participation) demonstrated different effects on influencing active participants' perceived constraints and subsequent coping strategies. Future investigations of coping strategies should continue to explore how active participants cope with onsite constraints based on a constraints-coping model in different settings.
7

Who is catching what? A survey of recreational fishing effort and success ontaiāpure and mātaitai management areas

Kallqvist, Emma January 2009 (has links)
Marine recreational fishing is a highly developed activity and has an increasingly global following. In New Zealand, over 30 % of the population participate in recreational fishing and the annual harvest of some species is larger than the commercial catch. It is therefore vital for resource management to include data on recreational take. Since marine recreational fishing and charter boat fisheries in New Zealand are managed outside the Quota Management System (QMS), Area Management Tools (AMT) such as taiapure (local fishery), mataitai (reserves) rahui (temporary closures) can be used to ensure sustainability of certain coastal areas affected by fishing and other activity. The Akaroa Harbour Taiapure was established in 2006 and is currently the only taiapure in Canterbury. The main objective with this study was to characterise the recreational fishery in the Akaroa Harbour Taiapure in order to provide management solutions for this area. Three surveys were set up whereby two were specifically designed to record the recreational take landed on the four most frequently used slipways in Akaroa Harbour. A third survey was to gauge local resident‟s perception on recreational fisheries over time. Both qualitative and quantitative methods were used and appropriate statistical analysis applied. Over 451 intercept interviews were conducted on slipways on Banks Peninsula and 138 trip records were returned. Main findings include significant differences in target and landed species, also a shift in areas mostly fished since the previous survey in 1997 by the Ministry of Fisheries. The most frequently landed fish in this study included blue cod, flounder, rock lobster and perch. The perception survey revealed a strong community bond to recreational fishing and a need for increased local input in the management of the Akaroa Harbour Taiapure. The three surveys are recommended to be continued over time in order to create a data base on recreational fishing and also to document local and indigenous knowledge on marine conservation.
8

The biology of Samson Fish Seriola hippos with emphasis on the sportfishery in Western Australia.

andrew@recfishwest.org.au, Andrew Jay Rowland January 2009 (has links)
This thesis had two overriding aims. The first was to describe the biology of Samson Fish Seriola hippos and therefore extend the knowledge and understanding of the genus Seriola. The second was to uses these data to develop strategies to better manage the fishery and, if appropriate, develop catch-and-release protocols for the S. hippos sportfishery. Trends exhibited by marginal increment analysis in the opaque zones of sectioned S. hippos otoliths, together with an otolith of a recaptured calcein injected fish, demonstrated that these opaque zones represent annual features. Thus, as with some other members of the genus, the number of opaque zones in sectioned otoliths of S. hippos are appropriate for determining age and growth parameters of this species. Seriola hippos displayed similar growth trajectories to other members of the genus. Early growth in S. hippos is rapid with this species reaching minimum legal length for retention (MML) of 600mm TL within the second year of life. After the first 5 years of life growth rates of each sex differ, with females growing faster and reaching a larger size at age than males. Thus, by 10, 15 and 20 years of age, the predicted fork lengths (and weights) for females were 1088 (17 kg), 1221 (24 kg) and 1311 mm (30 kg), respectively, compared with 1035 (15 kg), 1124 (19 kg) and 1167 mm (21 kg), respectively for males. Despite these differences, female and male S. hippos attained similar maximum age, i.e. 29 (1470 mm FL) and 28 years (1280 mm FL), respectively. The maximum age determined for S. hippos is greater than that recorded for any other Seriola spp. The largest female and male S. hippos recorded during this study were encountered during the tagging component and had fork lengths of 1600 mm and 1380 mm, respectively. Seriola hippos has a protracted spawning period, ca four months, which starts in late spring and continues through summer into early autumn during which time many individuals engage in large spawning aggregations on the lower west coast of Australia. The length at which 50 % of the females in the population reached maturity was 831 mm FL (888 mm TL) and approximately 4 years of age, whilst all females over 950 mm FL were mature. Whilst aggregated for spawning S. hippos ceases feeding, however, during the non-spawning period this species can best be described as an opportunistic carnivore which feeds on a variety of pelagic and demersal prey. This study has greatly increased our understanding of S. hippos movement on the west and south coasts of Australia and has documented, for the first time, the migratory behaviour of a carangid in these waters. Many S. hippos individuals undertake long distance migrations to join spawning aggregation sites near Rottnest Island. Individuals tagged at these aggregation sites where recaptured throughout this species distribution along the south coast of Australia, some after travelling distances of over 2400 km. Many S. hippos individuals displayed strong temporal and spatial spawning ground fidelity as numerous fish released at the spawning aggregations were recaptured at the exact same spawning site at similar times in subsequent years. Tagging data suggest that on the completion of spawning S. hippos individuals return to a resident location and remain in that general vicinity over the winter months. This study has developed a hypothesis describing larval dispersal associated with the S. hippos spawning behaviour exhibited near Rottnest Island. It is proposed that variations in the prevailing ocean currents, at this important spawning location throughout the protracted spawning period, leads to high intra and inter-annual variation in larval distribution and survival. The affect of this variation on the evolution of the spawning and migratory behaviour displayed by S. hippos is discussed. A recent increase in the popularity of S. hippos as a catch-and-release sportfish has led to concerns by some anglers about post release survival of this species, particularly due to the depth of capture. Short term mortality of S. hippos capture at the sportfishing sites was assessed by monitoring fish held within an enclosure near the site of capture for up to 31 hours post release. The total hooking mortality of S. hippos subjected to catch-and-release angling within the Rottnest Island sportfishery is approximately 8%. Most of this observed mortality is delayed and occurs sometime after release. Although best handling practises require ongoing development, the current level of mortality associated with this catch-and-release fishery is considered acceptable. Furthermore, this mortality is likely to have little effect on the S. hippos population due to the high abundance of this species and the fact that even the highest fishing effort yields a relatively low catch. Seriola hippos exhibits a typical teleost neuroendocrine stress response associated with catch-and-release. The physiological dysfunction associated with the stress of capture in this species does not appear to cause any post release mortality. Instead, most mortality was attributable to barotrauma, however, although mortality in S. hippos increases with capture depth, this species is much less susceptible to depth induced mortality than other commonly targeted species in which barotrauma has been observed. This study developed key handling protocols for fishers who catch-and-release S. hippos at the Rottnest Island aggregation sites. These protocols cover aspects of catch-and-release fishing such as hook type, water depth, time at surface, release method and shark predation. Almost all S. hippos observed during capture from deep water released large quantities of gas from the opercular region, particularly during the last 10 to 20 m before reaching the surface. This phenomenon has also been witnessed by divers and fishers to occur under natural conditions. Investigations into this release of gas revealed this physoclistous species to exhibit unique swim bladder characteristics. Seriola hippos possess a membranous tube that connects the posterior-dorsal surface of the swim bladder internally to a region under each operculum externally. This connection, termed the swim bladder vent, allows the escape of expanding swim bladder gases on rapid ascent. The presence of the swim bladder vent provides an explanation as to why the incidence of external barotrauma symptoms in S. hippos captured from the deepwater was low. The ability to expel excess swim bladder gases during rapid ascent whilst retaining full swim bladder function is likely to offer this semi-pelagic species considerable advantages when hunting prey, avoiding predators and engaging in spawning activities. Preliminary estimates of total mortality indicated that S. hippos is not currently subjected to a high level of fishing pressure. However, managers must remain mindful of the fact that the size at which females reach sexual maturity, i.e. 888 mm TL, is greater than the current minimum legal length, i.e. 600 mm, and thus fishers are currently allowed to harvest sexually immature fish. Furthermore, the effectiveness of future conservation measures must consider the large scale migration and spawning strategy undertaken by this species in order to ensure its protection. The collaborative research approach undertaken during this study demonstrated that a high level of community engagement produced a large amount of research interest, increased stakeholder satisfaction from project input, improved understanding of research outcomes, and increased research uptake, all of which has led to increased stewardship and conservation of the S. hippos fishery and fisheries resources in general. Indeed, projects of this nature would not be possible without this type of approach.
9

Biology, demography and conservation of rays in Moreton Bay, Queensland, Australia.

Simon Pierce Unknown Date (has links)
Thirteen elasmobranch species were collected during a four year seine-net survey of the intertidal margins of Moreton Bay, a large subtropical embayment in southeast Queensland, Australia. The inshore elasmobranch fauna of Moreton Bay is relatively species rich in comparison to sites elsewhere in Australia, emphasising the regional importance of this ecosystem. Stingrays were the most common large predators in the intertidal, with overall catches dominated numerically by the blue-spotted maskray Neotrygon kuhlii (53.8%) and the estuary stingray Dasyatis fluviorum (22.2%). The biological and demographic characteristics of these two species were examined in detail. Neotrygon kuhlii ranged in size from 11.5 – 46.5 cm disc width (WD), with 50% maturity in females at 31.4 cm WD and 6.32 years old and at 29.4 cm WD and 3.95 years in males. Neotrygon kuhlii has a synchronous annual reproductive cycle, producing one litter of 1 – 3 pups (mean of 1.67 ± 0.71 S.D.) in the late Austral summer after a four month gestation. Maximum age estimates of 13 and 10 years were obtained from females and male N. kuhlii, respectively. Annual band pair deposition was confirmed through the recapture of four wild calcein-injected individuals from 22.7 to 30.2 cm WD. A three parameter power function provided the best statistical fit to age-at-size data for both sexes, providing parameter estimates of y0 = 163.13, a = 58.52 and b = 0.58 for females and y0 = 165.13, a = 59.02 and b = 0.54 in males. Individual growth rates obtained from tagged specimens were not qualitatively different to modelled growth predictions. Tagging studies produced a total recapture rate of 16.1%, with individual rays at liberty for up to 1081 days. Direct estimates of instantaneous mortality for N. kuhlii were derived by creating catch curves for both sexes from age-frequency keys. Mortality was estimated at 0.171 ± 0.024.yr-1 S.E. in females, corresponding with a population growth rate of 1.00.yr-1 based on deterministic matrix demographic model predictions, and 0.345 ± 0.022.yr-1 S.E. in males. Seven age-independent and two age-dependent indirect mortality estimates produced negative population growth rates of 0.84 to 0.98.yr-1. Elasticity results were relatively robust to mortality estimates, with juvenile survivorship contributing 74-75% of total elasticity under all scenarios. Dasyatis fluviorum is endemic to near-shore, estuarine and riverine habitats along the eastern coast of Australia. Previous records of the species from northern Australia and New Guinea appear to be misidentifications of other, similar species. Dasyatis fluviorum was caught at 15.5 cm to 76.2 cm WD in Moreton Bay, with 50% maturity occurring at 63 cm WD (13.40 years) in females and 41.2 cm WD (6.97 years) in males. Maximum age estimates of 21 and 16 years were obtained from females and males, respectively. The Gompertz growth function provided the best fit to estimated age data in female D. fluviorum, providing parameter estimates of WD∞ = 100.3 cm, k = 0.09.yr-1 and t0 = 5.66. The modified two-parameter von Bertalanffy growth function provided the best fit to male size-at-age data, providing parameter estimates of WD∞ = 73.4 cm, k = 0.10.yr-1 and b = 0.86. An annual reproductive cycle in female D. fluviorum was hypothesised based on preliminary reproductive data. Fecundity estimates were derived from the related D. americana for input into deterministic and stochastic demographic models. Six out of nine indirect mortality estimates produced positive population growth in deterministic models, with a probabilistic estimate of 1.02.yr-1. Elasticity results were robust to model structure, mortality and fecundity estimates, with juvenile survivorship comprising 74-78% of total elasticity under all scenarios. Both N. kuhlii and D. fluviorum provide interesting case studies in elasmobranch conservation. Neotrygon kuhlii is a common bycatch of demersal prawn-trawl fisheries in Australia. Although mandatory turtle exclusion devices (TEDs) exclude most large vertebrates from trawl catches in Australian waters, their benefits in the reduction of smaller elasmobranch bycatch has not been empirically tested. The results of deterministic demographic models show that TEDs can, in principle, mitigate the impacts of trawl fisheries by partially excluding highly-elastic large juvenile age-classes. However, N. kuhlii is the largest of the four Neotrygon species found in Australian waters and bycatch of the three smaller species may be less reduced by current bycatch reduction technologies. Dasyatis fluviorum is affected by a suite of anthropogenic threats in its near-shore and estuarine habitats including commercial and recreational fisheries, habitat modification and pollution. Within Moreton Bay, 10.8% of the surveyed population bore evidence of past interactions with fisheries as evidenced by retained hooks or mutilated tails. Deep-hooking resulted in significant pathological effects including fibrocollagenous scar tissue masses, peritonitis and hepatitis. Stochastic demographic scenarios were created to model the potential effects of low (0.02 yr-1), medium (0.05 yr-1) and high (0.10 yr-1) rates of additive anthropogenic mortality to simulate stage-specific conservation interventions on D. fluviorum. Removing anthropogenic mortality on juvenile age-classes provided the largest benefits in terms of reducing population decline. The probability of the species’ conservation status declining further to Endangered, based on IUCN criteria, ranged from 39% to 100% under these mortality scenarios if no conservation measures were applied.
10

Biology, demography and conservation of rays in Moreton Bay, Queensland, Australia.

Simon Pierce Unknown Date (has links)
Thirteen elasmobranch species were collected during a four year seine-net survey of the intertidal margins of Moreton Bay, a large subtropical embayment in southeast Queensland, Australia. The inshore elasmobranch fauna of Moreton Bay is relatively species rich in comparison to sites elsewhere in Australia, emphasising the regional importance of this ecosystem. Stingrays were the most common large predators in the intertidal, with overall catches dominated numerically by the blue-spotted maskray Neotrygon kuhlii (53.8%) and the estuary stingray Dasyatis fluviorum (22.2%). The biological and demographic characteristics of these two species were examined in detail. Neotrygon kuhlii ranged in size from 11.5 – 46.5 cm disc width (WD), with 50% maturity in females at 31.4 cm WD and 6.32 years old and at 29.4 cm WD and 3.95 years in males. Neotrygon kuhlii has a synchronous annual reproductive cycle, producing one litter of 1 – 3 pups (mean of 1.67 ± 0.71 S.D.) in the late Austral summer after a four month gestation. Maximum age estimates of 13 and 10 years were obtained from females and male N. kuhlii, respectively. Annual band pair deposition was confirmed through the recapture of four wild calcein-injected individuals from 22.7 to 30.2 cm WD. A three parameter power function provided the best statistical fit to age-at-size data for both sexes, providing parameter estimates of y0 = 163.13, a = 58.52 and b = 0.58 for females and y0 = 165.13, a = 59.02 and b = 0.54 in males. Individual growth rates obtained from tagged specimens were not qualitatively different to modelled growth predictions. Tagging studies produced a total recapture rate of 16.1%, with individual rays at liberty for up to 1081 days. Direct estimates of instantaneous mortality for N. kuhlii were derived by creating catch curves for both sexes from age-frequency keys. Mortality was estimated at 0.171 ± 0.024.yr-1 S.E. in females, corresponding with a population growth rate of 1.00.yr-1 based on deterministic matrix demographic model predictions, and 0.345 ± 0.022.yr-1 S.E. in males. Seven age-independent and two age-dependent indirect mortality estimates produced negative population growth rates of 0.84 to 0.98.yr-1. Elasticity results were relatively robust to mortality estimates, with juvenile survivorship contributing 74-75% of total elasticity under all scenarios. Dasyatis fluviorum is endemic to near-shore, estuarine and riverine habitats along the eastern coast of Australia. Previous records of the species from northern Australia and New Guinea appear to be misidentifications of other, similar species. Dasyatis fluviorum was caught at 15.5 cm to 76.2 cm WD in Moreton Bay, with 50% maturity occurring at 63 cm WD (13.40 years) in females and 41.2 cm WD (6.97 years) in males. Maximum age estimates of 21 and 16 years were obtained from females and males, respectively. The Gompertz growth function provided the best fit to estimated age data in female D. fluviorum, providing parameter estimates of WD∞ = 100.3 cm, k = 0.09.yr-1 and t0 = 5.66. The modified two-parameter von Bertalanffy growth function provided the best fit to male size-at-age data, providing parameter estimates of WD∞ = 73.4 cm, k = 0.10.yr-1 and b = 0.86. An annual reproductive cycle in female D. fluviorum was hypothesised based on preliminary reproductive data. Fecundity estimates were derived from the related D. americana for input into deterministic and stochastic demographic models. Six out of nine indirect mortality estimates produced positive population growth in deterministic models, with a probabilistic estimate of 1.02.yr-1. Elasticity results were robust to model structure, mortality and fecundity estimates, with juvenile survivorship comprising 74-78% of total elasticity under all scenarios. Both N. kuhlii and D. fluviorum provide interesting case studies in elasmobranch conservation. Neotrygon kuhlii is a common bycatch of demersal prawn-trawl fisheries in Australia. Although mandatory turtle exclusion devices (TEDs) exclude most large vertebrates from trawl catches in Australian waters, their benefits in the reduction of smaller elasmobranch bycatch has not been empirically tested. The results of deterministic demographic models show that TEDs can, in principle, mitigate the impacts of trawl fisheries by partially excluding highly-elastic large juvenile age-classes. However, N. kuhlii is the largest of the four Neotrygon species found in Australian waters and bycatch of the three smaller species may be less reduced by current bycatch reduction technologies. Dasyatis fluviorum is affected by a suite of anthropogenic threats in its near-shore and estuarine habitats including commercial and recreational fisheries, habitat modification and pollution. Within Moreton Bay, 10.8% of the surveyed population bore evidence of past interactions with fisheries as evidenced by retained hooks or mutilated tails. Deep-hooking resulted in significant pathological effects including fibrocollagenous scar tissue masses, peritonitis and hepatitis. Stochastic demographic scenarios were created to model the potential effects of low (0.02 yr-1), medium (0.05 yr-1) and high (0.10 yr-1) rates of additive anthropogenic mortality to simulate stage-specific conservation interventions on D. fluviorum. Removing anthropogenic mortality on juvenile age-classes provided the largest benefits in terms of reducing population decline. The probability of the species’ conservation status declining further to Endangered, based on IUCN criteria, ranged from 39% to 100% under these mortality scenarios if no conservation measures were applied.

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