Effects of Exploitation on a Marten Population

The problem of evaluating the status of animal populations was encountered during a fur resource survey 2 in the Fort Nelson region of northern British Columbia. This paper deals with the possibility of analyzing catch records in order to evaluate the effects of exploitation on a population of marten (Martes americana actuosa). Marten specimens were collected from registered trap lines in an area of about 20,000 square miles during two trapping seasons, 1947-48 and 1948-49. These specimens totaled 127 and 123 in respective seasons and constituted about 16 per cent of the known kill for each year. Additional information useful for the interpretation of kill records was obtained in the field as reported by Quick (1953). The recent history of fur production in this region suggested that the trapping pressure was not detrimental to the population. Although a high level of fur production continued through at least eight years the gross production data did not provide a means of interpreting the status of the population or the effects of trapping pressure on the fauna. Data obtained from separate trap lines within the region revealed some variations that suggested the possibility of analyzing trapping pressure. One of the important population characteristics, sex ratio (of the kill), was readily determined. Variations in the sex ratio of the kills made by different trappers demonstrated that the timing of trapping operations resulted in selective sampling of the sexes. This has been reported in preliminary form (Quick, 1953). Another important population characteristic, age class determination, has not been satisfactorily worked out for the marten but Marshall (1951) has made progress on this subjec . The degree of development of the sagittal crest as an age class criterion has been described by Marshall and others. The sagittal crest characteristic was used in this study to classify marten skulls into groups (Table 1). Sagittal crest measurements were