Sawfish Download [UPD]
The sawfish package contains a window manager. This is useful for organizing and displaying windows where all window decorations are configurable and all user-interface policy is controlled through the extension language.
In this episode Jasmin Graham talks to Anders Halverson about her research on the ecology, movement, and range of smalltooth sawfish, one of Florida's critically endangered species. We then discuss the reasons Jasmin became a fisheries scientist and her work as the President, CEO, and co-founder of Minorities In Shark Sciences (MISS). Since different perspectives and voices drive the most innovative and impactful scientific research as well as the best natural resource management, how can the fisheries community recruit and retain a diverse pool of talent?
Are Rostra Distinct For Each Species?Rostra are different for each species with variations in tooth count, spacing between teeth and shape. For more information you can download the handy Sawfishes of the World Factsheet below.
All species are listed under Appendix I of CITES, which bans their international trade. But this doesn't prevent them from being caught in the first place. There are some national sawfish-specific protective measures in place. Yet these vary from country to country and enforcement of these laws is often poor. The US offers the strongest legal protection for the Largetooth and Smalltooth Sawfishes. Australia also offers protection but this varies across species and regions, and requires strengthening.
Morgan, D.L., Whitty, J.M., Phillips, N.M., Thorburn, D.C., Chaplin, J.A. & McAuley, R. (2011). North-western Australia as a hotspot for endangered elasmobranchs with particular reference to sawfishes and the Northern River Shark. Journal of the Royal Society of Western Australia 94: 345-358.
Phillips, N.M., Chaplin, J.A., Morgan, D.L. & Peverell, S.C. (2011). Population genetic structure and genetic diversity of three critically endangered Pristis sawfishes in northern Australian waters. Marine Biology 158: 903-915.
Phillips, N., Chaplin, J., Morgan, D. & Peverell, S. (2009). Extraction and amplification of DNA from the dried rostra of sawfishes (Pristidae) for applications in conservation genetics. Pacific Conservation Biology 15: 128-134.
Thorburn, D.C., Morgan, D.L., Rowland, A.J., Gill, H.S. & Paling, E. (2008). Life history notes of the critically endangered dwarf sawfish, Pristis clavata, Garman 1906 from the Kimberley region of Western Australia. Environmental Biology of Fishes 83: 139-145.
Whitty, J.M., Morgan, D.L., Peverell, S.C., Thorburn, D.C. & Beatty, S.J. (2009). Ontogenetic depth partitioning by juvenile freshwater sawfish (Pristis microdon: Pristidae) in a riverine environment. Marine and Freshwater Research 60: 306-316.
The freshwater sawfish (Pristis microdon) is a critically endangered elasmobranch. Ontogenetic changes in the habitat use of juvenile P. microdon were studied using acoustic tracking in the Fitzroy River, Western Australia. Habitat partitioning was significant between 0+ (2007 year class) and larger 1+ (2006 year class) P. microdon. Smaller 0+ fish generally occupied shallower water (0.6 m. Significant differences in hourly depth use were also revealed. The depth that 1+ P. microdon occupied was significantly influenced by lunar phase with these animals utilising a shallower and narrower depth range during the full moon compared with the new moon. This was not observed in 0+ individuals. Habitat partitioning was likely to be related to predator avoidance, foraging behaviours, and temperature and/or light regimes. The occurrence of 1+ P. microdon in deeper water may also result from a need for greater depths in which to manoeuvre. The present study demonstrates the utility of acoustic telemetry in monitoring P. microdon in a riverine environment. These results demonstrate the need to consider the habitat requirements of different P. microdon cohorts in the strategic planning of natural resources and will aid in the development of management strategies for this species.
Figure 5 (A) frequency of sawfish injuries at body, eye, mouth, and rostrom. (B) diagram of injury location classification on the smalltooth sawfish. (C) species being targeted when injury occurred. (D) life stages of sawfish when injury occurred.
The freshwater sawfish (Pristis pristis) was recently listed as the most Evolutionarily Distinct and Globally Endangered (EDGE) animal. The Fitzroy River in the remote Kimberley region of north-western Australia represents a significant stronghold for the species, which uses the freshwater reaches of the river as a nursery. There is also mounting pressure to develop the water resources of the region for agriculture that may substantially affect life history dynamics of sawfish in this system. However, the relationship between hydrology and population dynamics of freshwater sawfish was unknown. We used standardized catch data collected over 17 years to determine how wet season volume influences recruitment of freshwater sawfish into their riverine nursery. Negligible recruitment occurred in years with few days of high flood levels (above 98th percentile of cease-to-flow stage height), and relatively high recruitment occurred in years with 14 or more days of high flood levels. This relationship is indicative of a distinct boom-or-bust cycle, whereby freshwater sawfish rely almost entirely on the few years with large wet season floods, and the brief periods of highest water levels within these years, to replenish juvenile populations in the Fitzroy River nursery. This has direct implications for sustainable water resource management for the Fitzroy River basin in order to preserve one of the last known intact nursery habitats for this globally threatened species.
The Fitzroy River is a dryland river that operates under a monsoonal climate with extreme wet and dry seasons. Like many dryland rivers, it also has substantial inter-annual variability in discharge13,14,27, with annual wet season discharge varying more than 25 fold over the last 20 years (Government of Western Australia River Monitoring Stations; ). Such variability in discharge rates has been shown to affect recruitment and abundance of a variety of dryland river fish taxa9,10,28,29, although the relationship between river discharge and sawfish abundance has not been previously examined. Due to the low human population (
The present study uses long-term catch data from standardized freshwater sawfish surveys in the Fitzroy River to determine how river flow dynamics affect recruitment of freshwater sawfish into their riverine nurseries. Determining the relationship between hydrological parameters associated with wet season flood volumes and recruitment rates will help to inform the sustainable development and water allocation of the Fitzroy River, globally one of the last known intact nursery habitats for this highly threatened species.
Map (ArcGIS 10.2.1; -desktop) of sawfish survey locations in the Fitzroy River. Estuarine and freshwater survey locations are shown, along with the hydrological data collection site (Willare; red marker). Photographs show examples of habitat found in (A) King Sound near the river mouth, (B) Snag Pool (estuarine), (C) Camballin Pool (freshwater), and (D) Geikie Gorge (freshwater) (Photographs: D. Morgan).
Upon capture, sawfish were secured at the caudal fin by hand and at either the base of the rostrum by hand or at the tip of the rostrum by use of an entangled gill net (prior to the removal of the net from the rostrum). The spiracles, mouth and gills remained submerged during the handling of sawfish to allow for continued respiration. Morphometric data including total length (TL) and sex were recorded. Rototags (Dalton Tags, Nottinghamshire, UK) were attached to the first dorsal fins of animals32, and were individually numbered to assess recaptures of individuals within and between years. Once measured and tagged, sawfish were released at the site of capture.
In order to compare recruitment rates of freshwater sawfish during the survey period, catch per unit effort (CPUE) of young-of-the-year (YOY) freshwater sawfish in each year was calculated. YOY sawfish were defined as individuals measuring
Additionally, length-frequency histograms of sawfish were created for each year of the study. These histograms included all live sawfish caught during each year, including gill net, handline, and cast net captures. However, individual sawfish caught multiple times within a year (i.e. recaptured fish, determined by Rototag identification) were only included once per year. These histograms were examined to determine whether the dominant size class found in the Fitzroy River in a given year was related to years with high calculated recruitment rates.
Annual size frequency distributions for freshwater sawfish. Data include all freshwater sawfish caught in estuarine and freshwater pools in the Fitzroy River in each year between 2002 and 2018, including all capture methods. Note that the y-axes for 2011 and 2017 are to a different scale than the other years because of higher catch rates. Approximate sizes for age 0+ through 3+ sawfish are noted under the x-axis. Years with high flow wet seasons (notably 2009, 2011, and 2017) are characterized by high frequency of young of year individuals (
Relationship between recruitment of freshwater sawfish and wet season river flow. Graphs depict the relationship between the number of days during the wet season where river stage height exceeded the 98th percentile of water levels on record (the best fit segmented model) and recruitment rates of freshwater sawfish in the Fitzroy River, measured as catch per unit effort (CPUE) of young of year (YOY) individuals (total length
Long-lived and slow-maturing species including sawfishes are prone to extinction and require long-term ecological investigations in order to reveal patterns in life history and population dynamics17,23, particularly when ecosystem drivers, such as dryland flood rhythms, show high variability13,14. The current 17 year study provides an unprecedented perspective from which to clarify the hydrological requirements of the Fitzroy River catchment for rearing freshwater sawfish. Specifically, we report a clear relationship between wet season volume and recruitment success of freshwater sawfish in the Fitzroy River, highlighting the essential importance of brief and infrequent high water level periods for recruitment. Quantifying this recruitment threshold will be exceptionally valuable for informing management of water resources in the Fitzroy River, and highlights the benefit of long-term ecological monitoring for underpinning ecologically sustainable water resource and catchment management. 350c69d7ab