Finding the needle in the haystack: comparing sampling methods for detecting an endangered freshwater fish

2016 ◽  
Vol 67 (11) ◽  
pp. 1740 ◽  
Author(s):  
Mark Lintermans

Accurately detecting the presence or absence of threatened species is vital for threatened species management, and the detection power of individual sampling methods can vary significantly between species and life stages. The present study compares the detection power of six sampling methods in sampling the endangered Macquarie perch in riverine habitats in south-eastern Australia. In an initial survey in 1998 and 1999, fyke nets captured Macquarie perch at 100% of sites where the species was detected; gill-nets captured the species at 86%; with no other method having >50% detection efficiency. Most Macquarie perch were captured by fyke nets (90% in 1998 and 94% in 1999), followed by gill-nets (7 and 2%). A monitoring program at one of the survey sites over 7 years returned similar results with fyke nets detecting the species in all years. Fyke nets captured primarily young-of-year (YOY) individuals, whereas gill-nets captured adults and subadults. Boat electrofishing returned a high level of false negatives for Macquarie perch. Future sampling for this species should employ fyke and gill-nets to adequately characterise population structure (adults, juveniles, YOY), minimise false negatives and detect the occurrence of successful breeding the previous year.

2016 ◽  
Vol 22 (1) ◽  
pp. 3
Author(s):  
Kirby R. Smith ◽  
Carol Scarpaci ◽  
Brett M. Louden ◽  
Nicholas M. Otway

Underwater stereo-video photogrammetry was used to document the pectoral fin positions of various life-history stages of the critically endangered east Australian population of the grey nurse shark (Carcharias taurus) during normal swimming behaviour at multiple aggregation sites. A wide range in pectoral fin positions was recorded with dihedral pectoral fin angles ranging from –25 to 88°. Pectoral fin angles varied significantly among sites and this was attributed to the differing navigational and energetic requirements of the sharks. There was no significant relationship between pectoral fin angles and distances separating the shark and scuba diver. The wide range in pectoral fin angles, interactive use of the fins during swimming, low-energy behaviours of the sharks at aggregation sites and absence of ‘fight’ response agonistic behaviour indicated that the species does not exhibit agonistic pectoral fin depression. Reports of agonistic pectoral fin depression in the grey nurse shark obtained with visual estimates should be treated as preliminary observations requiring further testing using accurate sampling methods such as stereo photogrammetry. It is important that diver compliance with existing management guidelines that prohibit divers from chasing or harassing grey nurse sharks and blocking cave and gutter entrances is maintained.


2004 ◽  
Vol 58 (2) ◽  
pp. 145-158 ◽  
Author(s):  
Eric K. Brown ◽  
Evelyn Cox ◽  
P. L. (Paul L.) Jokiel ◽  
S. Ku'ulei Rodgers ◽  
William R. Smith ◽  
...  

1978 ◽  
Vol 26 (1) ◽  
pp. 175 ◽  
Author(s):  
GF Watson ◽  
MJ Littlejohn

A small area of overlap with hybridization characterizes the interaction between northern L. ewingi and L. paraewingi. Although significant levels of postmating isolation exist between the taxa, no evidence of reproductive character displacement in mating-call structure is apparent within the contact zone. No obvious environmental features appear to correlate with the position of the zone. Northern L. ewingi and L. verreauxi alpina also form a hybrid zone where their ranges meet, and the position of the zone appears to be correlated with altitude. The taxa are characterized by a high level of genetic compatibility and no mating-call differentiation is evident. However, despite hybridization with adjacent taxa, the distinctness of northern L. ewingi is maintained away from the areas of interaction, and hence it is considered specifically distinct from L. paraewingi and L. v. alpina. No natural interaction between northern L. ewingi and L. ewingi has been located. However, they are considered to be conspecific because of: their morphological resemblance; the high level of genetic compatibility between them; and, the similarity of each of their interactions with L. paraewingi and with L. v. alpina.


2021 ◽  
Author(s):  
Kristin Bianchini ◽  
Mark L. Mallory ◽  
Birgit Braune ◽  
Derek C.G. Muir ◽  
Jennifer F. Provencher

Contaminant levels and trends have been monitored in eggs of seabirds from the Canadian Arctic since 1975. Nearly 50 years of monitoring have provided key information regarding the temporal and spatial variation of various contaminant classes in different seabird species. However, previous work has primarily assessed individual or related contaminant classes in isolation. There is therefore a need to collectively consider all of the contaminants monitored in seabird eggs to determine where monitoring has been successful, to find areas for improvement, and to identify opportunities for future research. In this review, we evaluated monitoring data for the major legacy and emerging contaminants of concern in five seabird species from three High Arctic and three Low Arctic colonies in Canada. We review the history of Canada’s Arctic seabird egg monitoring program and discuss how monitoring efforts have changed over time; we summarize temporal, spatial, and interspecies variations in Arctic seabird egg contamination and identify important knowledge gaps; and we discuss future directions for ecotoxicology research using seabird eggs in Arctic Canada. Ultimately, this paper provides a high-level overview of the egg contaminant monitoring program and underscores the importance of long-term and continued seabird contaminant monitoring in Arctic Canada.


2017 ◽  
Vol 65 (2) ◽  
pp. 128
Author(s):  
Alex Arnold ◽  
Andrea Kodym ◽  
Nancy M. Endersby-Harshman ◽  
John Delpratt ◽  
Ary A. Hoffmann

Genetic studies can help guide effective ecological restoration by identifying potential source populations that contain the genetic variation necessary for adaptive potential, based on past landscape processes. Here we investigate genetic patterns in Gahnia radula (R.Br.) Benth., a sedge from south-eastern Australia that has potential for revegetation of disturbed areas. We developed microsatellite markers for this species and used them to show that it propagates mostly in a clonal manner. Levels of genetic variability differed between populations and the spatial scale of this variability within these populations is identified. A population used in recent restoration efforts and which sets seed has a particularly high level of variability. Recommendations are developed for sourcing material when using this sedge for revegetation.


2013 ◽  
Vol 64 (9) ◽  
pp. 775 ◽  
Author(s):  
Mark Lintermans

Freshwater fish are a highly threatened group and recovery of these threatened species is an increasingly difficult ecological and social challenge. There are many different on-ground recovery actions available to managers, but no synthesis of what, how or why these recovery actions have been deployed. The present paper reviews 428 reported on-ground recovery actions from a survey of practitioners of threatened freshwater-fish recovery in Australia. Recovery actions were grouped into 12 categories, with the most commonly utilised recovery categories being harvest control, translocation, habitat enhancement and stock enhancement. Major drivers of recovery actions were general conservation concern, recovery plans and emergency responses. The number of recovery actions grew significantly in the decade beginning 2000 as the impacts of prolonged drought in south-eastern Australia intensified. In all, 58% of recovery actions occurred in the Murray–Darling Basin, although this region holds only 27% of the 74 listed threatened freshwater fish in Australia. Few or no recovery actions were reported for many species, and few actions occurred in northern or western parts of the country. More than 80% of recovery actions reportedly had some form of monitoring. The diversity of management interventions is reviewed, and patterns and issues are identified to guide future recovery efforts.


2011 ◽  
Vol 59 (5) ◽  
pp. 295 ◽  
Author(s):  
Jack H. Pascoe ◽  
Robert C. Mulley ◽  
Ricky Spencer ◽  
Rosalie Chapple

South-east Australia has a complex predator assemblage which has historically been vulnerable to introduced species. This is the first Australian field study to analyse samples from members of the families Canidae, Dasyuridae, Strigidae, and Varanidae to describe the diet and diet overlap between these predators. Samples were collected opportunistically and hair and bone analysis was used to identify the content of samples. Wild dogs (Canis lupus) and lace monitors (Varanus varius) predominantly consumed large mammalian prey, which contributed to the high level of diet overlap (Ojk = 0.79) between these two species. Foxes (Vulpes vulpes) and spotted-tailed quolls (Dasyurus maculatus) also had a high level of diet overlap (Ojk = 0.76), a result of their diets containing a high proportion of medium-sized mammals. The diet of wild dogs and foxes showed moderate overlap (Ojk = 0.59), and foxes were more likely to prey on species within the critical weight range than on macropods, which made up a high proportion of the diet of wild dogs. These data confirm that significant diet overlap can occur between predators from different taxonomic classes and further investigation of potential competition will be important to ongoing management.


2013 ◽  
Vol 778 ◽  
pp. 779-785 ◽  
Author(s):  
Luís Jorge ◽  
Alfredo M.P.G. Dias

The cross-laminated timber panels (X-Lam panels) are produced for structural use in Service Classes 1 and 2 conditions, in accordance with what is established on Eurocode 5 [. Timber boards are glued together on orthogonal layers, allowing the panel to perform two important characteristics: good dimensional stability and loading in two-way directions. The influence of wood moisture content on the feasibility of cross-laminated timber is described in this paper regarding the dimensional stability of the panels when applied in high moisture locations. Several European Technical Approvals, state the low importance of the dimensional variations with moisture content of this type of panel, but some reference values can be found in other technical documents. The French Avis Technique [[[1 reference the value of 0.01mm/m for in-plane deformation (per percentage of timber moisture variation) and the TRADA Wood Information Sheet, WIS 2/3-62 [1, refers the maximum value of 0.02mm/m for the same conditions.The use of the X-Lam panels in Service Class 3 can not be used, concerning the high level of stressing in glue lines, and no producer has yet certified it for this Service Class. Moreover, the French Avis Technique doesnt allow the use of X-Lam panels in swimming-pools due to high hygrometry, even for conditions corresponding to Service Class 2.Cross laminated timber panels are widely used across Europe but are giving the first steps in Portugal at the moment. The first big project was finished in spring 2012 in Almada, comprising a building integrating a 25 meter in-door swimming-pool and a gym. In order to assess the behavior of the timber structure, due to the non-conventional using of the X-Lam panels, a monitoring program was started immediately after building construction. The results obtained are presented and discussed in this paper.


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