Imagine that we want to determine how many bass are in a local fishing pond using a mark-recapture study. The simplest method to estimate how many fish are in the pond is called the Peterson method also known as the Lincoln-Peterson index. To do this, we catch as many bass as we can in one trip, which is our sampling.
Before releasing the fish back in the pond, we mark them in some way with an external tag, fin clip, dye, PIT tag , etc.
Then, when we come back on the next trip, we catch fish again and count how many marked and unmarked bass are in our new sample. The proportion of marked bass recaptured out of the total number marked can be used to expand the number of unmarked bass caught on the second trip to a total population abundance. This is the case with our ongoing study to estimate the population size of striped bass in the San Joaquin River using fyke traps and mark-recapture methods.
The bass that we capture in our fyke traps are marked externally with numbered disc or spaghetti tags, and also tagged internally with PIT tags. Need help with Biology? One to one online tuition can be a great way to brush up on your Biology knowledge.
Answered by Georgie C. Answered by Chantal R. Answered by Liam P. We deployed camera traps to study free-ranging cats in National Wildlife Refuges and state parks on Big Pine Key and Key Largo and used spatial models to estimate cat population dynamics and stable isotope analyses to examine cat diets.
We provide evidence that cat groups within a population move different distances, exhibit different activity patterns, and that individuals consume wildlife at different rates - all of which have implications for managing this invasive predator. Common eider numbers are declining throughout most of their range. The cause of this decline is not known, but poor recruitment, declining food resources, hunting, poor survival are possible causes.
Research goals of this project focus on understanding the effects of hunting and predation on survival and recruitment rates of American common eiders Somateria mollissima in the Atlantic coast population, especially Maine. The project uses traditional band analysis methodologies as well as mark -recapture methods. Select islands and archipelagos in the Gulf of Maine constitute the study area.
Eiders are captured by hand nets and in drive traps and banded with standard USGS bands. Over the last 10 years, we have returned to the same islands to band unmarked birds and record bands of previously banded birds.
Analyses are ongoing to determine survival, recruitment, and recovery rates of Eiders in Maine. The ultimate goal is to provide information that can be included in specific management models for declining migratory bird populations. Royle, J. For decades, capture-recapture methods have been the cornerstone of ecological statistics as applied to population biology. Furthermore, capture-recapture does not invoke any spatially explicit biological processes and thus is distinctly non-spatial, accounting neither for the inherent spatial nature of the sampling nor of the spatial distribution of individual encounters.
Linking observed encounter histories of individuals to mechanisms of spatial population ecology will enable ecologists to study these processes using new technologies such as noninvasive genetics, remote cameras and bioacoustic sampling. Biologists at USGS Patuxent, as well as cooperating agencies are constantly looking for new ways of answering questions about the status of animal populations and how animal populations change over time.
To address these questions, data are collected on captures and or sightings of animals which can be used to estimate parameters which affect the population using legacy software.
Over time, new questions and methods for addressing these questions arise which require new computer software. Elastomer marks on a Turquoise darter Etheostoma inscriptum , used in mark-recapture to estimate fish survival in relation to streamflow variability.
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