Review of the exploitation of marine resources of the Australian Indian Ocean Territories: the implications of biogeographic isolation for tropical island fisheries

The small islands of the Indian Ocean Territories are isolated reefs in an expanse of open ocean of abyssal depth. The majority of marine species that live on their reefs and lagoons have settled there from remote locations. Colonising individuals are presumed to have come to the island as the result of unusual weather and current conditions and form populations that are, necessarily, largely self-sustaining. The isolated populations that make up many of the fish and invertebrate stocks at the Cocos (Keeling) and Christmas Islands rely almost exclusively on larvae returning to their home reef to settle, grow and ultimately reproduce to maintain their numbers. This insularity is, in many cases, a direct implication of the constraints imposed on species by their own biology and reproductive strategy. In the event that a species is lost from either of the islands, recolonisation is dependent on reoccurrence of the unusual colonisation events. The vulnerability of these stocks is further exacerbated by the tiny size of the islands. The small reefs and lagoon only have the capacity to sustain small stocks of fish and invertebrates, ones that are very much at risk to chance events such as localised overfishing, anoxia events or over predation

Human Capacity Building for Introduced Marine Pest Monitoring in Western Australia FRDC Report – Project 2009/319 Tactical Research Fund

OBJECTIVES: 1. To identify gaps in the Western Australian skill and knowledge base for the monitoring of introduced marine pests. 2. To establish a centralised source of skills and knowledge in W.A. to facilitate the planning, evaluation, and quality control of activities relating to Introduced Marine Pest (IMP) monitoring. 3. To provide an Australian best practice example and knowledge base to facilitate the consistent, effective and efficient implementation of the National Monitoring system for IMPs

Likelihood of Marine Pest introduction to the Indian Ocean Territories

The introduction of new species to environments in which they did not evolve has been widely recognised as one of the top five threats to marine ecosystem function and to biodiversity (Millennium Ecosystem Assessment, 2005)

Ecological Risk Assessment for the Temperate Demersal Elasmobranch Resource

In March 2021, the Department of Primary Industries and Regional Development (Department) convened an ecological risk assessment (ERA) of the fisheries that access the Temperate Demersal Elasmobranch Resource (Resource). ERAs are conducted by the Department as part of its Ecosystem Based Fisheries Management framework

Establishment of a taxonomic and molecular reference collection to support the identification of species regulated by the Western Australian Prevention List for Introduced Marine Pests

Introduced Marine Pests (IMP, = non-indigenous marine species) prevention, early detection and risk-based management strategies have become the priority for biosecurity operations worldwide, in recognition of the fact that, once established, the effective management of marine pests can rapidly become cost prohibitive or impractical. In Western Australia (WA), biosecurity management is guided by the “Western Australian Prevention List for Introduced Marine Pests” which is a policy tool that details species or genera as being of high risk to the region. This list forms the basis of management efforts to prevent introduction of these species, monitoring efforts to detect them at an early stage, and rapid response should they be detected. It is therefore essential that the species listed can be rapid and confidently identified and discriminated from native species by a range of government and industry stakeholders. Recognising that identification of these species requires very specialist expertise which may be in short supply and not readily accessible in a regulatory environment, and the fact that much publicly available data is not verifiable or suitable for regulatory enforcement, the WA government commissioned the current project to collate a reference collection of these marine pest specimens. In this work, we thus established collaboration with researchers worldwide in order to source representative specimens of the species listed. Our main objective was to build a reference collection of taxonomically vouchered specimens and subsequently to generate species-specific DNA barcodes suited to supporting their future identification. To date, we were able to obtain specimens of 75 species (representative of all but four of the pests listed) which have been identified by experts and placed with the WA Government Department of Fisheries and, where possible, in accessible museums and institutions in Australasia. The reference collection supports the fast and reliable taxonomic and molecular identification of marine pests in WA and constitutes a valuable resource for training of stakeholders with interest in IMP recognition in Australia. The reference collection is also useful in supporting the development of a variety of DNA-based detection strategies such as real-time PCR and metabarcoding of complex environmental samples (e.g. biofouling communities). ThePrevention List is under regular review to ensure its continued relevance and that it remains evidence and risk-based. Similarly, its associated reference collection also remains to some extent a work in progress. In recognition of this fact, this report seeks to provide details of this continually evolving information repository publicly available to the biosecurity management community worldwid

Review of the exploitation of marine resources of the Australian Indian Ocean Territories: the implications of biogeographic isolation for tropical island fisheries

The small islands of the Indian Ocean Territories are isolated reefs in an expanse of open ocean of abyssal depth. The majority of marine species that live on their reefs and lagoons have settled there from remote locations. Colonising individuals are presumed to have come to the island as the result of unusual weather and current conditions and form populations that are, necessarily, largely self-sustaining. The isolated populations that make up many of the fish and invertebrate stocks at the Cocos (Keeling) and Christmas Islands rely almost exclusively on larvae returning to their home reef to settle, grow and ultimately reproduce to maintain their numbers. This insularity is, in many cases, a direct implication of the constraints imposed on species by their own biology and reproductive strategy. In the event that a species is lost from either of the islands, recolonisation is dependent on reoccurrence of the unusual colonisation events. The vulnerability of these stocks is further exacerbated by the tiny size of the islands. The small reefs and lagoon only have the capacity to sustain small stocks of fish and invertebrates, ones that are very much at risk to chance events such as localised overfishing, anoxia events or over predation

A long way from home: Biosecurity lessons learnt from the impact of La Niña on the transportation and establishment of tropical portunid species.

Marine ecosystems can be modified and shaped by irregular interannual variations in oceanic current patterns and temperatures, such as El Niño and La Niña. These large scale oceanic events have also been shown to influence environmental stressors such as invasive marine species (IMS). Our study indicates that there is a causative link between these climatic events, and atypical detections of native and IMS. Significant La Niña events between 1970 and 2014 were associated with sightings of tropical crab species in temperate waters following a lag period of 18-24 months from the onset of the event. We identified a total of 72 records of six tropical portunid crabs species (from both Charybdis and Scylla) in temperate waters of south-western Australia following these La Niña events, based on reports in published scientific literature, grey literature and museum records, as well as citizen science networks such as FishWatch and PestWatch apps. We suggest that La Niña conditions facilitated transportation and temporary establishment of crab larvae from their native tropical habitat to temperate regions. As the strength of La Niña events is likely to increase into the future due to the escalating effects of climate change, it is likely that there will be a growth in associated atypical establishment events of IMS. Consequently, biosecurity managers will need to reprioritise resources in order to accommodate the potential impacts of these large scale oceanic events as part of their surveillance programmes

Ecological Risk Assessment for the Temperate Demersal Elasmobranch Resource

In March 2021, the Department of Primary Industries and Regional Development (Department) convened an ecological risk assessment (ERA) of the fisheries that access the Temperate Demersal Elasmobranch Resource (Resource). ERAs are conducted by the Department as part of its Ecosystem Based Fisheries Management framework