In Britain the schelly populations are usually considered as members of the widespread Eurasian whitefish species Coregonus lavaretus, or common whitefish, as with the Welsh gwyniad and Scottish powan.[2][3][4] This is supported by morphological evidence, as a review was unable to find any solid evidence for treating them as separate.[5] The schelly is listed as a distinct species of whitefish, C. stigmaticus, in FishBase and by the IUCN.[1][6]
At Haweswater, the fishery officers are now culling all of the cormorants that visit the lake, in order to protect the endangered fish. An analysis of reservoir management data over a 30-year period (1961–1991) has revealed that the decline of the schelly population is associated with increased water abstraction and reduced water levels. Entrapment during abstraction is not significant. Year class strength is probably determined by lake levels during the January–March spawning and incubation period whereas subsequent growth rate is influenced by lake levels during June–October.
^Maitland, P. S.; Lyle, A. A.; Barnett, I. K. O. (1990). "Status of the schelly, Coregonus lavaretus (L.), in Red Tarn, Cumbria, England". Journal of Natural History. 24 (4): 1067. Bibcode:1990JNatH..24.1067M. doi:10.1080/00222939000770641.
^Etheridge, E.C.; C. E. Adams; C. W. Bean; N. C. Durie; A. R. D. Gowans; C. Harrod; A. A. Lyle; P. S. Maitland; I. J. Winfield (2012). "Are phenotypic traits useful for differentiating among a priori Coregonus taxa?". Journal of Fish Biology. 80 (2): 387–407. Bibcode:2012JFBio..80..387E. doi:10.1111/j.1095-8649.2011.03189.x. PMID22268437.