Conservation, Ecology, and Management of Catfish: The Second International Symposium

2011 ◽  
Keyword(s):  
Native Species ◽  
Size Structure ◽  
Total Mortality ◽  
Small Fish ◽  
Total Biomass ◽  
Flathead Catfish ◽  
History Of ◽  
Native Fishes ◽  
Negative Impacts ◽  
Annual Mortality

<em>Abstract</em>.—Recent modeling indicates that increased exploitation on nonnative flathead catfish <em>Pylodictis olivaris</em> may be an avenue for native species recovery. Flathead catfish were illegally introduced into the Satilla River, Georgia, and negative impacts have occurred on native fishes. In an effort to aid in the restoration of native fish on the Satilla River, the Georgia Department of Natural Resources initiated an intensive electrofishing removal effort. In this study, we evaluated the changes in flathead catfish total mortality, condition, and size structure from those efforts. From 2007 to 2009, 13,472 flathead catfish totaling 19,337 kg were removed along a 129-km stretch of the Satilla River. The population size structure changed substantially from containing many large individuals (59% 510 mm total length [TL]) in 2007 to mainly small fish (79% 356 mm TL) by 2009. Total biomass per effort declined from 57.05 kg/h in 2007 to 19.96 kg/h in 2009. Mean individual weight of fish removed decreased from 2.64 kg in 2007 to 1.32 kg in 2008 to 0.61 kg in 2009. Population age structure was also truncated, but there was evidence for higher recruitment and earlier maturation, which would require that intensive harvest be maintained to prevent the population from rebuilding within 2–5 years. Catch-curves revealed increasing total annual mortality rates of 37, 48 and 52%, for 2007–2009, respectively. Considering the life history of the flathead catfish, being a long-lived species that presumably cannot withstand excessive rates of exploitation (i.e., greater than 25% exploitation), our results indicated that an electrofishing removal program is a reasonable management option for areas where this apex predator has been introduced, but continual removal may be required to maintain low biomass.

Size-Structured Morality in a Treespine Stickleback (Gastrosteus aculeatus) – Cutthroat Trout (Oncorhynchus clarki) Community

1990 ◽  
Vol 47 (6) ◽  
pp. 1194-1205 ◽  
Author(s):  
T. E. Reimchen
Keyword(s):  
Gasterosteus Aculeatus ◽  
Size Structure ◽  
Adult Population ◽  
Total Mortality ◽  
Cutthroat Trout ◽  
Oncorhynchus Clarki ◽  
Small Fish ◽  
Frequency Distributions ◽  
Queen Charlotte Islands ◽  
Young Of The Year

In a 112-ha bog lake on the Queen Charlotte Islands, British Columbia, small fish comprised the major element in the diet of cutthroat trout (Oncorhynchus clarki). Despite the presence of juvenile salmon and char in the lake, threespine stickleback (Gasterosteus aculeatus) was the most common fish in the diet (99.5%). Foraging activity appeared to be more frequent in littoral than in limnetic regions. Mark–recapture methods indicate an average population of 220 trout and 75 000 adult stickleback. Trout consumed an estimated 308 770 stickleback yearly (145 kg) of which 65% were taken during summer. Seventy-three percent of all fish consumed were young of the year and 2% were adults, the latter representing 4% of the adult population in the lake. There was a 75% reduction in total mortality between successive year classes of stickleback (0,1,2,3 +). This consumption curve, which resembles a typical survivorship curve of fish, is a function of the size-structure of the populations and includes interactions between size availability of stickleback, prey-size preferences of the trout, and length frequency distributions of trout. Total weight of stickleback consumed by trout comprised about 40% of that previously calculated for 16 species of avian piscivores in the lake.

scholarly journals A Field Guide to Freshwater Fishes, Crayfish and Mussels of South-Western Australia.

2012 ◽  
Vol 18 (2) ◽  
pp. 148
Author(s):  
Tim Blake
Keyword(s):  
Western Australia ◽  
Native Species ◽  
Small Fish ◽  
Introduced Fish ◽  
Community Groups ◽  
Mosquito Fish ◽  
South West ◽  
History Of ◽  
History Of The South ◽  
Crayfish Species

MORGAN et al. have filled a significant gap in the library of pictorial guides to the fauna of South- Western Australia with this publication. This pocketsized edition is a must for anyone who has any interest in the natural history of the South West as well as schools, community groups and anyone who wishes to start investigating the fauna of our rivers. Not only will this guide help anyone with identification, but it will alert them to the very existence of so many native species. Perhaps any small fish will no longer be written off as a “mosquito fish” and elicit a more detailed look. It is quite surprising that there are only 11 native species of fish in the whole south-west province but impressive that 9 are endemic – the highest ratio in any part of Australia. The presence of as many crayfish species (11), many of very limited distribution, is also of note. However, it is quite disturbing that 12 (and likely more) introduced fish species are also listed for identification. A further reflection is that only 1 fish and 3 crayfish in the whole of Australia are on the Critically Endangered list under the Environmental Protection and Biodiversity Conservation Act 1999 – all of these are in the area covered by the guide.

scholarly journals Invasive Alien Species of Bangladesh

2020 ◽  
Author(s):  
Sharif A. Mukul ◽  
Khan Mohammed Abu Sayed Arfin ◽  
Mohammad Belal Uddin
Keyword(s):  
Alien Species ◽  
Native Species ◽  
Invasive Alien Species ◽  
Environmental Benefits ◽  
Species Introduction ◽  
Statutory Body ◽  
History Of ◽  
Negative Impacts ◽  
Trade Route ◽  
Early Modern Era

Bangladesh has a history of species introduction from different geographic regions. The country was a major trade route during the early-modern era and was under British colonial rule until 1947s. Many species of plants and animals are either domesticated or cultivated at different times that were brought into the country by the settlers, seamen, and traders. The deliberate preferences of fast-growing, high-yielding exotics in recent decades also threaten the existence of native species and their genetic resources in the country. Here we provide an overview of the invasive alien species in Bangladesh, likely pathways of their introduction, their impacts on ecosystem and people, and strategies for their effective management and regulation. Many exotic plants and animals both terrestrial and aquatic have found to be invasive in the country with negative impacts on local ecosystems, biodiversity, and livelihoods. Collectively, those species possess serious threats to country&rsquo;s agriculture, forestry, and fisheries sector. Although initially introduced to favor primary productivity or other environmental benefits, many of these are now regarded as obnoxious pest or weed in Bangladesh. A comprehensive list of invasive species both for native and exotics and a framework to characterize them is also absent in the country. We recommend a separate statutory body and appropriate rules and policies for the introduction, monitoring, and management of alien species in the country. Community awareness, advocacy, surveillance, capacity building of relevant government staff and agreement with neighboring countries for transboundary management of invasive alien species is also necessary.

scholarly journals Nesting, Sex Ratio and Natural Enemies of the Giant Resin Bee in Relation to Native Species in Europe

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 545
Author(s):  
Sara Straffon Díaz ◽  
Luca Carisio ◽  
Aulo Manino ◽  
Paolo Biella ◽  
Marco Porporato
Keyword(s):  
Sex Ratio ◽  
Natural Enemies ◽  
Native Species ◽  
Wild Bees ◽  
Trap Nests ◽  
Native Bee ◽  
New Locations ◽  
Negative Impacts ◽  
Set Up ◽  
North Western

Megachile sculpturalis (Smith, 1853) is the first exotic bee species in Europe. Its remarkably fast expansion across this continent is leading to a growing concern on the extent of negative impacts to the native fauna. To evaluate the interactions of exotic bees with local wild bees, we set up trap nests for above-ground nesting bees on a semi-urban area of north-western Italy. We aimed to investigate the interaction in artificial traps between the exotic and native wild bees and to assess offspring traits accounting for exotic bee fitness: progeny sex ratio and incidence of natural enemies. We found that the tunnels occupied by exotic bees were already cohabited by O. cornuta, and thus the cells of later nesting alien bees may block the native bee emergence for the next year. The progeny sex ratio of M. sculpturalis was strongly unbalanced toward males, indicating a temporary adverse population trend in the local invaded area. In addition, we documented the presence of three native natural enemies affecting the brood of the exotic bee. Our results bring out new insights on how the M. sculpturalis indirectly competes with native species and on its performance in new locations.

scholarly journals Predicting the potential distribution of the vase tunicate Ciona intestinalis in Canadian waters: informing a risk assessment

2008 ◽  
Vol 65 (5) ◽  
pp. 788-794 ◽  
Author(s):  
Thomas W. Therriault ◽  
Leif-Matthias Herborg
Keyword(s):  
Risk Assessment ◽  
Native Species ◽  
Potential Distribution ◽  
Negative Impact ◽  
Ciona Intestinalis ◽  
Environmental Niche ◽  
Environmental Models ◽  
Introduced Range ◽  
Negative Impacts ◽  
Almost All

Abstract Therriault, T. W., and Herborg, L-M. 2008. Predicting the potential distribution of the vase tunicate Ciona intestinalis in Canadian waters: informing a risk assessment. – ICES Journal of Marine Science, 65: 788–794. A crucial step in characterizing the potential risk posed by non-native species is determining whether a potential invader can establish in the introduced range and what its potential distribution could be. To this end, various environmental models ranging from simple to complex have been applied to predict the potential distribution of an invader, with varying levels of success. Recently, in marine waters, tunicates have received much attention, largely because of their negative impacts on shellfish aquaculture. One of these species is the vase tunicate Ciona intestinalis, which recently has had a negative impact on aquaculture operations in Atlantic Canada and could pose a risk in Pacific Canada. To inform the risk assessment of this species, we evaluated two different types of environmental model. Simple models based on reported temperature or salinity tolerances were relatively uninformative, because almost all waters were deemed suitable. In contrast, a more complex genetic algorithm for rule-set prediction (GARP) environmental niche model, based on documented Canadian occurrence points, provided informative projections of the potential distribution in Canadian waters. In addition to informing risk assessments, these predictions can be used to focus monitoring activities, particularly towards vectors that could transport C. intestinalis to these favourable environments.

Homeostatic Characteristics of Single Species Fish Stocks in Arctic Lakes

1983 ◽  
Vol 40 (7) ◽  
pp. 987-1024 ◽  
Author(s):  
Lionel Johnson
Keyword(s):  
Stock Returns ◽  
Dominant Species ◽  
Size Structure ◽  
Arctic Charr ◽  
Arctic Lakes ◽  
Large Individual ◽  
Total Biomass ◽  
Length Frequency ◽  
Initial State ◽  
Fish Stocks

The results of investigations on the fish stocks of seven Arctic lakes covering a period of 23 yr are described. These lakes have remained largely undisturbed since their formation in late glacial times; all but one are completely autonomous and of comparatively small size. Such lakes provide a unique opportunity for the development and testing of conceptual models. In all cases the only fish species present is Arctic charr, Salvelinus alpinus. Length frequency distributions derived from gillnet catch curves are shown to be, within reasonable limits, representative of the actual populations in the lake, and not artifacts of the sampling procedure. Length frequency curves show a unimodal or bimodal distribution and this structure, in the absence of perturbation, appears to remain constant indefinitely. Individuals are of great age but age-at-length is highly variable. Age and size structure are shown to be comparable with the age and size structure of the dominant tree species in a climax forest; it is concluded that forces of great generality fashion these configurations. It is hypothesized that all species tend to move towards a state of least energy dissipation; this can be most readily seen in the dominant species at the climax in an autonomous system. The dominant species is characterized by large individual size, a high degree of uniformity, high total biomass, great mean age, indeterminate age-at-death, and a low incidence of replacement stock. After severe perturbation it is shown that the charr stock returns to a state of least dissipation without oscillation. Absence of oscillation during the return to the initial state, combined with the long-term stability shown in control lakes, indicates the presence of an effective damping mechanism; this in turn indicates the existence of organization within the stock as a whole. Organization develops through an interactive mechanism described under the doctrine of homeokinesis, which is responsible for energy equipartitioning and the maintenance of uniformity. These concepts help to explain phenomena observed in more complex systems and help our understanding of ecosystem functioning.

First Nations’ Survivance and Sovereignty in Canada during a Time of COVID-19

2020 ◽  
Vol 44 (2) ◽  
pp. 89-100
Author(s):  
Robyn K. Rowe ◽  
Julia Rowat ◽  
Jennifer D. Walker
Keyword(s):  
First Nations ◽  
Healthcare System ◽  
Scarlet Fever ◽  
Nations People ◽  
Vulnerable People ◽  
History Of ◽  
Negative Impacts ◽  
First Nations People

First Nations people in Canada have demonstrated and continue to demonstrate persistent and resilient cultural, linguistic, and traditional endurance: survivance. The devastation resulting from centuries of health pandemics such as smallpox, influenza, cholera, tuberculosis, measles, and scarlet fever reinforce the ongoing resilience of First Nations people, cultures, and traditions in Canada. Despite the history of pandemic-related trauma and a myriad of social, political, environmental, and health challenges, as well as the added burden that COVID-19 is placing on the healthcare system in Canada, First Nations’ organizations and leadership are enacting their inherent rights to sovereignty and governance. While First Nations are bracing for the expected negative impacts of COVID-19, they are doing so in ways that respect and honor their histories, cultures, languages, and traditions. First Nations are acting to protect some of the most vulnerable people in their communities including elders, knowledge keepers, and storytellers who carry with them irreplaceable traditional and cultural knowledges.

Imazapic Effects on Competition Dynamics Between Native Perennial Grasses and Downy Brome (Bromus tectorum)

2015 ◽  
Vol 8 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Shayla A. Burnett ◽  
Brian A. Mealor
Keyword(s):  
Native Species ◽  
Relative Yield ◽  
Perennial Grasses ◽  
Downy Brome ◽  
Replacement Series ◽  
Application Timing ◽  
Ecosystem Disturbance ◽  
Series Design ◽  
Species Establishment ◽  
Negative Impacts

AbstractDowny brome inhibits revegetation efforts following ecosystem disturbance. Imazapic is a commonly used herbicide for downy brome management, but more information is needed regarding effective application timing for restoration efforts. We wished to determine (1) if native species establishment exhibited a tradeoff between downy brome competition and injury from herbicide and (2) if this differed between pre- and postemergent applications of imazapic. We used a standard replacement series design and overlaid herbicide treatments. Nine weeks after planting, aboveground biomass was harvested and relative yield (RY) indices calculated. Both imazapic applications reduced downy brome biomass by 91% or more (P < 0.05). Imazapic caused drastic reductions in native biomass but less than what was caused by downy brome competition (P < 0.05). Natives were less injured by a pre- than postemergent application (P < 0.05). In situations where downy brome may impact restoration efforts, pre-emergent applications of imazapic at 70 g ai ha−1 (0.06 lb ai ac−1) may reduce downy brome with less negative impacts on newly-seeded native grasses than post-emergent applications. Ensuring sufficient proportions of native species seeds on restoration sites may reduce downy brome.

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