Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1980.tb02775.x

Stomach contents analysis—a review of methods and their application

Amphibians are frequently characterized as having limited dispersal abilities, strong site fidelity and spatially disjunct breeding habitat. As such, pond-breeding species are often alleged to form metapopulations. Amphibian species worldwide appear to be suffering population level declines caused, at least in part, by the degradation and fragmentation of habitat and the intervening areas between habitat patches. If the simplification of amphibians occupying metapopulations is accurate, then a regionally based conservation strategy, informed by metapopulation theory, is a powerful tool to estimate the isolation and extinction risk of ponds or populations. However, to date no attempt to assess the class-wide generalization of amphibian populations as metapopulations has been made. We reviewed the literature on amphibians as metapopulations (53 journal articles or theses) and amphibian dispersal (166 journal articles or theses for 53 anuran species and 37 salamander species) to evaluate whether the conditions for metapopulation structure had been tested, whether pond isolation was based only on the assumption of limited dispersal, and whether amphibian dispersal was uniformly limited. We found that in the majority of cases (74%) the assumptions of the metapopulation paradigm were not tested. Breeding patch isolation via limited dispersal and/or strong site fidelity was the most frequently implicated or tested metapopulation condition, however we found strong evidence that amphibian dispersal is not as uniformly limited as is often thought. The frequency distribution of maximum movements for anurans and salamanders was well described by an inverse power law. This relationship predicts that distances beneath 11–13 and 8–9 km, respectively, are in a range that they may receive one emigrating individual. Populations isolated by distances approaching this range are perhaps more likely to exhibit metapopulation structure than less isolated populations. Those studies that covered larger areas also tended to report longer maximum movement distances – a pattern with implications for the design of mark-recapture studies. Caution should be exercised in the application of the metapopulation approach to amphibian population conservation. Some amphibian populations are structured as metapopulations – but not all.

Dispersal and the metapopulation paradigm in amphibian ecology and conservation : are all amphibian populations metapopulations?

Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Al- though the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conser- vation and management, it is important to define core habitats used by local breeding populations surround- ing wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats sur- rounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands (19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feed- ing, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core hab- itats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wet- land and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.

/pdf/biological-criteria-for-buffer-zones-around-wetlands-and-1of77ixc63.pdf

Biological Criteria for Buffer Zones around Wetlands and Riparian Habitats for Amphibians and Reptiles

(1977). An Epitaph for the Concept of Maximum Sustained Yield. Transactions of the American Fisheries Society: Vol. 106, No. 1, pp. 1-11.

An Epitaph for the Concept of Maximum Sustained Yield

Stable nitrogen isotope ratios ( delta 15N) are commonly used to represent the trophic structure of aquatic systems, yet the ability of delta 15N to indicate the trophic position of aquatic consume...

http://people.uleth.ca/~joseph.rasmussen/pdfs/VanderZanden-etal1997.pdf

Comparing trophic position of freshwater fish calculated using stable nitrogen isotope ratios (δ15N) and literature dietary data

OBSERVATIONS over several years have shown that most streams which enter the Finger Lakes in central New York are visited annually by a run of large common suckers, Catostomus c. commersonnii (Lacepede). At this time suckers are taken by angling and by spearing. This is especially true of the lake suckers which reach a large size (see Table III). They are an important local food fish and might be utilized to a greater extent during the next few years. Much of the information to be presented below may be useful in connection with the pond culture of the muskalonge, Esox masquinongy. Here the problem involves supplying an abundance of living forage fishes of varying sizes for the young muskalonge after they have eaten the available stock of Daphnia and similar small animals. Suckers may be stripped, the eggs incubated in jars, and the young raised in small ponds until they are of the desired length. If eggs are obtained several times during the sucker run, a plentiful supply of all sizes of suckers would result. A number of incidental notes on these migrations in New York State waters have appeared in the literature. Surface (1899: 241) observed the run to last from the last of March to the middle of May in Cayuga .Lake Inlet. In Beebe Lake, at Ithaca, Stewart (1927: 150) found that the spawning season lasted approximately one month, and ended on May 25. Greeley and Bishop (1932: 81) report a spawning run as early as April 13 to 15 in Fish Creek at Pope's Mills. Greeley (1930: 77) also found them breeding as late as June 17 in Stacy Brook, a tributary of Lake Champlain. The most complete studies on migrating suckers are those by Dence (1937 and 1940) on the dwarf white sucker, Catostomus commersonnii utawana Mather. Mather (1886), Kendall and Dence (1929: 287), Greeley and Greene (1931: 84), Greeley and Bishop (1932: 81), and Greeley (1934: 101) have noted that the dwarf subspecies, utawana, spawns later than the common white sucker where they occur at the same locality in the Adirondack Mountains. Migrations of utawana usually occur in June. In Michigan some interesting data on sucker migration were obtained by Shetter (1938: 335). A two-way fish trap was operated continuously over one calendar year (1937) in Canada Creek, Presque Isle County. He found that the greatest number of suckers taken in April and May were moving downstream, possibly out of small lakes to spawning grounds. He also found a considerable number of suckers moving both upstream and downstream during September and October. During the spring of 1939 an attempt was made to obtain a picture of the sucker migration in Skaneateles Lake Inlet. This was possible since a weir had been installed in connection with research on the rainbow trout, Salmo gairdnerii, by Dr. H. John Rayner, of the Laboratory of Limnology and Fisheries, Cornell University. The sucker studies covered a general description of the main characteristics of the run, and included the length

The Spring Migration of the Common White Sucker, Catostomus c. commersonnii (Lacepede), in Skaneateles Lake Inlet, New York

During the summer of 1939 the movements of 237 tagged bullfrogs, Rana catesbeiana Shaw, were studied at the Edmund Niles Huyck Preserve, at Rensselaerville, Albany County, New York. These frogs were marked by locking numbered monel metal tags around the dentary bone. The results were reported by Raney (1940). Other studies on the growth of these bullfrogs in nature have been reported by Raney and Ingram (1940 and 1941). Additional returns on 22 individuals recaptured by Ingram in the summer of 1940, and 12 records obtained by Dr. Jean Piatt during 1941 serve as a basis for these notes.

Additional Studies on the Movement of Tagged Bullfrogs, Rana catesbeiana Shaw

of digestion, should not affect the ratio of the rates for the different organisms. This should be tested experimentally. It is acknowledged that the data submitted above only indicate that a difference in the rate of digestion of different kinds of organisms does occur; and they are not sufficient for the actual determination of evaluation factors. The latter should be determined with larger samples according to the method outlined above.

Observations on the Life History of the Spotted Darter, Poecilichthys maculatus (Kirtland)

l ITTLE information on food habits based on the examination of stomach contents is available for the queen snake, Natrix septemvittata (Say). The few scattered data indicate crayfish are the most important food, a fact fully substantiated by this study. The common water snake, Natrix sipedon sipedon (Linnaeus), eats mostly fishes and amphibians, and smaller amounts of insects and mammals. This study is concerned with the food habits of the two species taken in the same habitat.

Food and Growth of Two Species of Watersnakes from Western New York

, AND B. W. EVERMANN. 1896. The fishes of North and Middle America. Pt. 1. Bull. U. S. Natl. Mus. 47:1-1240. LINCK, H. F. 1790. Versuch einer Eintheilung der Fische nach den Zahnen. Mag. Neu. Phys. Naturges. 6(1):28-38. LINNAEUS, C. 1758. Systema Naturae. Tom. 1, Ed. 10. ii-824 pp. MILLER, R. R. 1957. Origin and dispersal of the alewife, Alosa pseudoharengus, and gizzard shad, Dorosoma cepedianum, in the Great Lakes. Trans. Am. Fish. Soc. 86(1956): 97-111. REGAN, C. T. 1916. The British fishes of the subfamily Clupeinae and related species in other seas. Ann. Mag. Nat. Hist. Ser. 8, 18: 1-19. 1917. A revision of the clupeoid fishes of the genera Pomolobus, Brevoortia and Dorosoma and their allies. Ibid. 19:297-316. SVETOVIDOV, A. N. 1932. Sur le rapport entre le caractere de la nourriture et la nombre des appendices pyloriques chez les harengs. Comp. Rend. Acad. Sci. URSS A (8):202-204. 1952a. O zavisimosti mezhdu colichestvom pulorichescikh pridatcov i kharacteram pitanya ryb. (On the correlation between the number of pyloric caeca and the character of food in fishes.) Ocherki po obschim voprosam ikhtyologyi. Akad. Nauk SSSR:282-289. 1952b. Seldevye (Clupeidae). Fauna SSSR. Ryby 2(1), 331 pp.

Edward C. Raney

Papers

The Spring Migration of the Common White Sucker, Catostomus c. commersonnii (Lacepede), in Skaneateles Lake Inlet, New York

Additional Studies on the Movement of Tagged Bullfrogs, Rana catesbeiana Shaw

Observations on the Life History of the Spotted Darter, Poecilichthys maculatus (Kirtland)

Food and Growth of Two Species of Watersnakes from Western New York

Etheostoma moorei, a New Darter of the Subgenus Nothonotus from the White River System, Arkansas