As recreational fishers act relatively autonomously, management relies heavily on voluntary compliance. Therefore, understanding fishers’ views on management options can be beneficial. This study ...used a two-phase approach of face-to-face interviews and subsequent online questionnaires to evaluate recreational fishers’ salient views on issues affecting the Blue Swimmer Crab (Portunus armatus) and Black Bream (Acanthopagrus butcheri) fisheries in Western Australia as well as current and potential management arrangements, including stock enhancement. The strength and heterogeneity of views were also determined. Minimum size limits were mainly considered acceptable or very acceptable, with restricting recreational fishing and spatial closures the least supported management options for both species, in addition to maximum size limits for crabs. These views were not always consistent across fishing locations for each species and among types of crab fishers, indicating heterogeneity in views. Stocking was the most acceptable of the management measures not already utilised for crabs and among the most popular for bream fisheries. Recreational fishers of both species believed stock enhancement could have strong positive outcomes for the abundance of their target species and increase their subsequent catches. They also recognized that some negative outcomes, e.g., increased fishing pressure and environmental issues, might occur but considered them unlikely.
Abstract
The taxonomy of the ocean sunfishes (Molidae) has a complicated history. Currently, three genera and four species are recognized, including two in the genus Mola (M. mola and M. ramsayi). In ...2009, a genetic study revealed a potential third species, Mola species C, in Southeast Australian waters. Concentrating on this region, we obtained samples and morphological data from 27 Mola sp. C specimens, genetically confirmed the existence of this species (mtDNA D-loop and cytochrome c oxidase 1), and established its morphology across a size spectrum of 50–242 cm total length. Mola sp. C is diagnosed by clavus meristics 15–17 fin rays (13–15 principal, 2 minor), 5–7 ossicles, paraxial ossicles separate, clavus morphology (prominent smooth band back-fold, rounded clavus edge with an indent), and body scale morphology (raised conical midpoints, non-branching). This species does not develop a protruding snout, or swollen dorso- or ventrolateral ridges. Body proportions remain similar with growth. A review of the historic literature revealed that Mola sp. C is a new, hitherto undescribed species, M. tecta, which we describe and diagnose, and that it is the first proposed addition to the genus Mola in 125 years. Its core distribution is likely in the temperate waters of the Southern Hemisphere.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics ...and movements. We investigate the population structure and residency patterns of reef manta rays (Mobula alfredi) in the Nusa Penida Marine Protected Area (MPA). From photo-identification data logged by citizen scientists and trained observers (mantamatcher.org), we identified 624 reef manta rays from 5,913 sightings (January 2012-April 2018) based on their unique ventral coloration patterns. Year-round records were collected from two shallow (< 20 m) reefs- Manta Bay (MB; n = 3,029 sightings) and Manta Point (MP; n = 3,058)- that are used frequently by tourism operators. Maximum likelihood techniques and a Markov movement analysis were used to model residency patterns and movement between these sites within the MPA. Manta rays at MB were predominantly male (64%, n = 261 individuals), with immature males (14%, n = 59) being sighted most frequently (39%, n = 1,170). In contrast, few immature individuals were sighted at MP (6%, n = 28), and they were sighed on few occasions (2%, n = 45), while mature female manta rays comprised 26% (n = 127) of the MP community and were the most frequently sighted (48%, n = 1,413). Lagged Identification Rates indicated high site fidelity at each location. However, 44% (n = 278) of individuals moved between the two sites and cumulative discovery curves showed a continued recruitment of individuals over the 6 years of the study. In addition, the behaviors displayed by the manta rays differed markedly between the two sites: MB appears to be a foraging ground, especially for juveniles, and potentially a nursery, while MP is used mainly for cleaning and courtship, indicating a social and reproductive site. Reproductive behavior coincided with the peak annual sightings in May. To prevent disturbance to this threatened species by tourism, regulations for the number of vessels and interactions, especially during key reproductive times should be considered. Further, strict fishing regulation in the area is recommended as fishing gear entanglement was identified as a threat to this population.
Diet and trophic role of octopus on an abalone sea ranch Greenwell, Claire N.; Loneragan, Neil R.; Tweedley, James R. ...
Fisheries management and ecology,
December 2019, 2019-12-00, 20191201, Letnik:
26, Številka:
6
Journal Article
Recenzirano
Gastric tract (crop and stomach) and stable isotope analyses (SIA) were used to evaluate the dietary composition of resident, commercially important Octopus aff. O. tetricus Gould, and its importance ...as a predator of Haliotis laevigata Donovan, on artificial abalone habitats. Taxonomic diversity and resolution of diet were higher in crops (13 taxa) than stomachs (10 taxa), with the latter dominated by unidentifiable material (%Volume = 74%). Crops contained mainly molluscs (~54%, including 31% abalone) and crustaceans (33%), suggesting octopus are important predators of abalone on the sea ranch. Dietary composition of crops did not differ with increasing octopus weight (<300 g, 300–999 g, ≥1,000 g wet weight), paralleling the findings of SIA and reflecting the high stocking densities of abalone that are able to be consumed by octopus of all sizes. The SIA also revealed that octopus occupy a mid‐trophic level, slightly below teleosts and loliginid squids.
Sustainable natural resource management requires collaboration, adaptability and coordination between science, policy and stakeholders. Communication of scientific information through social networks ...is integral to effective governance. This study employed social network analysis to investigate information flow between stakeholders associated with the blue swimmer crab (Portunus armatus) fishery in the Peel-Harvey Estuary, south-western Australia. Although the fishery received Marine Stewardship Council certification in 2016, a preliminary study conducted between 2017 and 2018 revealed that fishers were concerned about its status and management. Consequently, 85 face-to-face interviews were conducted with commercial and recreational fishers, academics, government bodies, representatives of fishing organizations, non-governmental organizations, and tourism organizations to understand the flow of information and the influence on perceptions of sustainability. The results showed that: i) Few individuals were key for sharing information within and between different organizations forming the fishery network and only two of the six groups (government bodies and the commercial fishing sector) were highly connected and appeared as key for information sharing; ii) After the public sector stakeholders, academic groups were the second-least connected, despite having actively researched the Peel-Harvey Estuary and the P. armatus fishery for over 40 years; iii) Recreational fishers exchanged information mainly with other fishers and the regional fisheries department, rather than the organization representing recreational fishers; iv) Modes of communication used with the recreational fishing sector greatly differed between the fisheries department (i.e., mainly via phone/email) and the recreational fishing organisation (i.e., strong online presence, social media and phone/email); v) Issues of inclusiveness and representation were highlighted for some of the groups and organizations. This study has identified logistical and institutional difficulties to communicate information regarding the science, management and environmental issues related to a small-scale crab fishery, providing managers and other stakeholders with a pathway of action for enhancing resource management.
Humpback whales
Megaptera novaeangliae
undertake extensive annual migrations, have complex migratory patterns, and have held several mammalian long-distance movement records. Here, we report on a ...whale known to feed in the Russian Far East that was sighted in breeding areas on either side of the North Pacific, the Mariana Islands and Mexico, in less than 1 yr (357 d apart). This is the longest published distance (11261 km great-circle route) between 2 unique sightings of a photo-identified humpback whale to date. To understand the context of this movement, we investigated records of whales that had been sighted in Russian feeding areas and Mexican breeding areas using historic and newly available photo-identification data. We found 117 humpback whales documented in both countries between 1998 and 2021, revealing a substantial increase from the only 11 matches that were previously known. These whales exhibited high site fidelity to Mexico, with one-third seen in multiple years, and up to 10 yr. However, we also found that they changed breeding areas more frequently than Mexico whales matched to other feeding areas, illustrating how the Mariana Islands-Mexico movement may have occurred. We document the first complete round-trip migrations between Mexico and Russia, a journey of >16400 km, the longest known migration of Northern Hemisphere humpback whales. Our data demonstrate regular trans-Pacific movements of humpback whales in the North Pacific, highlighting the importance of Mexico for the species ocean-basin-wide and the need for effective local management to aid in the conservation of multiple at-risk distinct population segments.
Prey density has long been associated with prey profitability for a predator, but prey quality has seldom been quantified. We assessed the potential prey availability and calorific value for ...Indo-Pacific bottlenose dolphins (Tursiops aduncus) in an estuarine and coastal environment of temperate south-western Australia. Fish were sampled using three methods across three regions (Estuary, Bay and Ocean) in the study area using a 21.5 m beach seine, multi-mesh gillnet, and fish traps. The total biomass and numbers of all species and those of potential dolphin prey were determined in austral summers and winters between 2007 and 2010. The calorific value of 19 species was determined by bomb calorimetry. The aim of the research was to evaluate the significance of prey availability in explaining the higher abundance of dolphins in the region in summer versus winter across years. A higher abundance of prey was captured in the summer (mean of two summer seasons ± 1 SE = 12,080 ± 160) than in the winter (mean of two winter seasons = 7,358 ± 343) using the same number of gear sets in each season and year. In contrast, a higher biomass of potential dolphin prey, of higher energy content, were captured during winters than summers, when fewer dolphins are present in the area. Variability was significant between season and region for the gillnet (p < 0.01), and seine (p < 0.01). The interaction of season and region was also significant for the calorific content captured by the traps (p < 0.03), and between the seasons for biomass of the trap catch (p < 0.02). The dolphin mother and calf pairs that remain in the Estuary and Bay year round may be sustained by the higher quality, and generally larger, if lesser abundant, prey in the winter months. Furthermore, factors such as predator avoidance and mating opportunities are likely to influence patterns of local dolphin abundance. This study provides insights into the complex dynamics of predator – prey interactions, and highlights the importance for a better understanding of prey abundance, distribution and calorific content in explaining the spatial ecology of large apex predators.
Non-indigenous species are recognised as a significant threat to estuaries as they can negatively impact native fauna and ecosystem functioning. This study compared the abundance and distribution of ...the introduced gobiid, Acentrogobius pflaumii, with native gobiids in the shallow, nearshore and deeper, offshore waters of the Swan-Canning Estuary over 31 consecutive months and determined the influence of salinity and water temperature on the gobiid assemblage. Eight gobiid species were recorded (six native and two non-indigenous). Each species was present in offshore waters, with five also occurring in nearshore waters. The contribution of A. pflaumii to the gobiid fauna varied markedly between depths, not being recorded in the 1240 samples from nearshore waters, but representing almost half of all gobiids caught in offshore waters. The percentage contribution of this species to the total gobiid abundance declined with distance from the estuary mouth, from 96% in the most downstream region to only 0.4% in the uppermost. The overwhelming contributions of A. pflaumii in the lower estuary, which historically contained few gobiids, indicate that it has successfully exploited an unoccupied niche. Gobiid composition, in both depths, differed mainly among regions, with species partitioning themselves along the longitudinal axis of the estuary. In offshore waters, Favonigobius lateralis and A. pflaumii dominated the lower regions and Arenigobius bifrenatus, Favonigobius punctatus and Pseudogobius olorum the regions further upstream. The distributions of these species are influenced by salinity and, to a lesser extent, temperature. While there is spatial overlap between A. pflaumii and native gobiid species, its preference for deeper, more saline waters may limit the impact of this non-indigenous species.
Management strategy evaluation using the Method Evaluation and Risk Assessment (MERA) platform was used to evaluate management procedures (MPs) for improving the management of the leopard coral ...grouper (Plectropomus leopardus) fishery in Saleh Bay, Indonesia. This grouper is a valuable species currently under high fishing pressure. It is targeted by small-scale fisheries using a wide range of fishing methods; hence, management recommendations are needed to ensure sustainability. A suite of MPs for data-limited conditions were evaluated for their ability to achieve limit and target biomass reference points (B/BMSY = 0.5 and B/BMSY = 1, respectively), while maintaining a target yield of at least 0.5 MSY. The simulation results suggest that the currently implemented harvest control rules (HCRs) in Saleh Bay (size limit and spatial closure) may not be effective in achieving the management objective to attain the target biomass reference point due to relatively low compliance with the size limit regulation (320 mm total length) and the very small proportion of existing MPA no-take areas (~2.2%). This study recommends that the fisheries management authority explores the feasibility of implementing the total allowable catch (TAC) and seasonal closure in addition to the existing fishing regulations for P. leopardus in Saleh Bay.
Vessel strike is recognized as a major modern threat to the recovery of large whale populations globally, but the issue is notoriously difficult to assess. Vessel strikes by large ships frequently go ...unnoticed, and those involving smaller vessels are rarely reported. Interpreting global patterns of vessel strikes is further hindered by underlying reporting biases caused by differences in countries’ research efforts, legislation, reporting structures and enforcement. This leaves global strike data “patchy” and typically scarce outside of developed countries, where resources are more limited. To explore this we investigated vessel strikes with large whales in the Eastern Tropical Pacific (ETP), a coastal region of ten developing countries where heavy shipping and high cetacean densities overlap. Although this is characteristic of vessel strike “hotspots” worldwide, only 11 ETP strike reports from just four countries (∼2% of total reports) existed in the International Whaling Commission’s Global Ship Strike Database (2010). This contrasts greatly with abundant reports from the neighboring state of California (United States), and the greater United States/Canadian west coast, making it a compelling case study for investigating underreporting. By reviewing online media databases and articles, peer review publications and requesting information from government agencies, scientists, and tourism companies, we compiled a regional ETP vessel strike database. We found over three times as many strike reports (
n
= 40), from twice as many countries (
n
= 8), identifying the geographic extent and severity of the threat, although likely still underestimating the true number of strikes. Reports were found from 1905 until 2017, showing that strikes are a regional, historic, and present threat to large whales. The humpback whale (
Megaptera novaeangliae
) was the most commonly hit species, and whale-watch industries involving small vessels in areas of high whale densities were recognized as a conservation and management concern. Industrial fishing fleets and shipping were suggested to be underrepresented sectors in the database, and are likely high-risk vessels for strikes with whales. We demonstrate the implications of known vessel strike reporting biases and conclude a more rapid assessment of global vessel strikes would substantially benefit from prioritized research efforts in developing regions, with known vessel strike “hotspot” characteristics, but few strike reports.
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