Age Estimation, Growth Rates, and Population Structure in Missouri Bullfrogs

Copeia ◽  
1968 ◽  
Vol 1968 (3) ◽  
pp. 583 ◽  
Author(s):  
Eugene E. Schroeder ◽  
Thomas S. Baskett
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Age Estimation

Population structure, age and growth rates of conifer species and their relation to environmental variables at Malam Jabba, Swat District, Pakistan

2018 ◽  
Vol 31 (2) ◽  
pp. 429-441
Author(s):  
Arsalan ◽  
Muhammad Faheem Siddiqui ◽  
Moinuddin Ahmed ◽  
Syed Shahid Shaukat ◽  
Alamdar Hussain
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Environmental Variables ◽  
Age And Growth ◽  
Conifer Species

The spatial distribution of illegal logging in the Anavilhanas archipelago (Central Amazonia) and logging impacts on species

2011 ◽  
Vol 39 (2) ◽  
pp. 111-121 ◽  
Author(s):  
ANDRESSA BÁRBARA SCABIN ◽  
FLÁVIA REGINA CAPELLOTTO COSTA ◽  
JOCHEN SCHÖNGART
Keyword(s):  
Growth Rate ◽  
Population Structure ◽  
Spatial Distribution ◽  
Growth Rates ◽  
Market Value ◽  
Southern Region ◽  
Illegal Logging ◽  
Negative Effects ◽  
Human Settlements ◽  
Harvesting Intensity

SUMMARYAmazonia is one of the world's leading suppliers of timber and the Amazonian timber industry is an important source of regional income, however the economic benefits of this market are associated with environmental damage, mainly when the wood is removed illegally. The Anavilhanas National Park, located in the Brazilian state of Amazonas, has been subjected to illegal logging and elaboration of control programmes requires knowledge of the distribution of timber species and the intensity of logging. This study examines the density and growth rate of the five most harvested tree species in the Park, the spatial distribution of illegal logging operations and their effects on population structure. In total, 2332 trees with diameter at breast height greater than 10 cm, as well as stumps of cut trees, were sampled, and dendrochronology was used to estimate growth rates. Some size classes of Virola surinamensis trees and species within the family Lauraceae decreased in abundance as harvesting intensity increased. Growth rates of the most abundant species of Lauraceae, Ocotea cymbarum, were high, indicating stands may recover quickly when harvesting stops. The population structure of Calophyllum brasiliense showed no negative effects due to logging, but its low growth rate and stand distribution suggest that continued exploitation may endanger these populations. Logging had no detectable negative effects on the size structure of populations of Macrolobium acaciifolium or Hevea spp., and their high growth rates suggest that they will not be threatened by current logging rates. Overall growth rates in the Anavilhanas archipelago are higher than those recorded in other black-water floodplain forest (igapó). Logging of most species (except Lauraceae spp., which have the highest market value) is concentrated in the southern region of the Park, which has more human settlements close by. There was no general relationship between harvesting intensity and geographic distance to human settlements, but there was a tendency for harvesting to be higher in sites with concentrations of trees of high market value. Potential strategies to control illegal logging activities in the Anavilhanas archipelago include encouragement of sustainable logging in Park buffer zones and stimulation of ecotourism initiatives in the southern region of the Park. Ecotourism development can provide an economic alternative to illegal logging for local communities and inhibit logging by increasing vigilance.

scholarly journals The demographics and morphometries of biogenic reefs: important considerations in conservation management

2017 ◽  
Vol 98 (6) ◽  
pp. 1231-1240 ◽  
Author(s):  
Jenna M. Brash ◽  
Robert L. Cook ◽  
Clara L. Mackenzie ◽  
William G. Sanderson
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Conservation Management ◽  
Tidal Flow ◽  
Growth Curves ◽  
Shell Morphology ◽  
Published Data ◽  
Marine Habitat ◽  
Juvenile Abundance ◽  
Horse Mussel

Modiolus modiolus L. (horse mussel) reefs are a priority marine habitat of high conservation value that is currently listed as endangered and/or threatened across its European distribution. Population structure, density or shell morphology may influence the biodiversity of a reef, either directly or indirectly. Thus, such metrics are important considerations for successful conservation management of these biodiversity hotspots. Population structure, shell morphology and growth rates were examined in M. modiolus reefs across the UK range of the habitat to examine differences between key populations, including those near the Lleyn Peninsula in Wales (southern range), off Port Appin in Western Scotland (mid-range) and in Scapa Flow in the Orkney Isles, Scotland (northern range). Additionally, the influence of physical conditions (temperature and tidal flow) to growth rate and predicted maximum shell length for each population was examined. Growth rates were determined using acetate peels of sectioned shells. Lower juvenile abundance was observed in Scapa Flow. Small, narrow-shaped shells were found to be characteristic of North Lleyn mussels, and larger, globular-shaped shells were characteristic of mussels in Scapa Flow and off Port Appin. Mussels in Scapa Flow were slower growing, yet reached a longer asymptotic length (L∞) than mussels of Port Appin and North Lleyn. Growth curves from sites within this study were analysed with other published data. A trend of higher L∞ at higher latitudes and at lower flow rates was observed. Variations in growth and age are discussed in relation to flow regimes, connectivity to other reefs, density and latitude.

Growth and age validation of Rainbow Trout, Oncorhynchus mykiss (Walbaum)' in Lake Eucumbene, NSW

1992 ◽  
Vol 43 (5) ◽  
pp. 1033 ◽  
Author(s):  
RA Faragher
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Growth Rates ◽  
Age Estimation ◽  
New South ◽  
Age Validation ◽  
Scale Reading ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
South Wales ◽  
Second Year

Growth rates of finclipped rainbow trout (Oncorhynchus mykiss) released into Lake Eucumbene, New South Wales, at an age of 0+ years were examined for each year between 1986 and 1988. Traps and nets yielded significant numbers of marked fish for validation of age estimation and length backcalculation from scale reading. Poor recognition of the marks by anglers was confirmed, indicating that survival of the fish was higher than was implied by angling returns. The diffuse nature of the second annulus in scales provided initial difficulty in ageing, particularly because of a similarly diffuse false check formed during the second year. Care was required in separating the annuli after asymptotic growth was reached (3 years), Growth rates in Lake Eucumbene were comparable with those found in studies in Tasmania and Victoria. Back-calculated lengths were in agreement with those from fish of known ages. The presence of finclipped fish aged 2 + and 3 + years in a spawning population confirmed that stocked fish contributed to the spawning stocks. The study reconfirms the importance of validation of ageing techniques in fisheries investigations.

Advances in Fish Tagging and Marking Technology

2012 ◽  
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Inductively Coupled Plasma ◽  
Sexual Maturity ◽  
Current Data ◽  
Otolith Chemistry ◽  
Inductively Coupled ◽  
Spatial Differences ◽  
General Movement ◽  
The 1960S

<i>Abstract</i>.—The population structure of the eastern Australian salmon <i>Arripis trutta </i>stock in the waters of southeastern (SE) Australia was examined using information provided by historical as well as current data sources. An extensive tag-recapture program and aging study undertaken during the 1960s demonstrated widespread mixing of the <i>A. trutta </i>population in SE Australian waters and established a robust model of general movement of fish from Tasmania north to Victoria and NSW with the approach of sexual maturity at ~four years of age. However, this work also hypothesized that the portion of the stock at Flinders Island in Tasmanian waters was resident and did not undergo this northward migration. Otolith chemistry analyses were therefore used as a tool in a ‘weight of evidence’ approach to further examine the population structure of the <i>A. trutta </i>stock in SE Australia. Samples of five year old <i>A. trutta </i>for analysis of otolith chemistry were collected over seven weeks from two sites (10 per site) within each of four locations: northern NSW, southern NSW, Victoria and Tasmania. The cores and edges of otoliths were analyzed using laser ablation inductively coupled plasma mass spectrometry. Univariate analyses did not find spatial differences for any of the elements Li, Na, Mg, Mn, Ba or Sr between locations. Multivariate analyses however, did find differences between the multi-element ‘fingerprints’ of fish from Tasmania compared to each of the other locations (which were similar). This difference was driven by a group of fish collected from Flinders Island in north-eastern Tasmanian waters. The fish collected at this site were also significantly smaller at five years of age than fish from all other sites, indicating reduced growth rates. The lack of consequential and definitive differences in otolith chemistry data combined with the highly migratory nature of <i>A. trutta </i>in this region demonstrated by tagging studies confirm that the most likely stock structure model for <i>A. trutta </i>in SE Australia is of a single well mixed biological stock spanning Tasmania, Victoria and NSW with fish moving north from Tasmania to mainland Australia with the approach of sexual maturity. However, the reduced growth rates and distinct elemental signature for <i>A. trutta </i>from Flinders Island highlights the need for further work to examine the preexisting hypothesis of a potential resident sub-population there.

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