Multivariate Morphometric Variability in Pacific Salmon: Technical Demonstration

Abstract

A computer oriented approach to the collection and analysis of morphometric characteristics in juvenile chinook salmon (Oncorhynchus tshawytscha) is described. A three-step data collection and storage method is used whereby X–Y coordinate data for relevant morphological features on a body form are collected with a digitizing pad and used to calculate morphometric characters. To test this method, I calculated two morphometric data sets, a conventional and a truss network, and compared them by multivariate analysis in a preliminary study of growth and development in one hatchery stock of fish, and in a survey of population differences in three naturally occurring populations of chinook salmon. Technical advantages of using a digitizing pad for collecting morphometric data are demonstrated. Hatchery-reared chinook salmon showed marked changes in body shape during the period of spring smoltification when marked changes in condition factor occurred. Multivariate differences were discerned among the three Oregon coastal stocks. Truss data provided more specific information concerning shape changes in the study of early development and produced greater between-group differences in the geographic survey. The results of these preliminary analyses can be applied to problems of identifying smolt status in hatchery fish and stock origin in mixed-stock fisheries.

Morphological Variations in Astacus Astacus L. And Austropotamobius Pallipes (Lereboullet) Populations

“…In marine and freshwater fish the use of morphometric measurements is common for stock identification and often used as for example in chinook salmon Oncorhynchus tshawytscha (Walbaum in Artedi, 1792) (WINANS, 1984), horse mackerel Trachurus trachurus (L.) (MURTA, 2000), australian bass Macquaria novemaculeata (Steindachner, et al, 1999). Our results on crayfish species demonstrated successful classification when discriminant analysis was used.…”

“…Since decades, morphometric measurements combined with multivariate analysis offer a good tool to explore differences between single groups of organisms (SAILA and FLOWERS 1969;WINANS, 1984;MURTA, 2000;PALMA and ANDRADE, 2002). According to these authors, the morphology of an animal usually reflects its environment.…”

Marine Growth and Morphometrics for Three Populations of Atlantic Salmon from Eastern Maine, USA

“…A truss network of morphometric characters (Strauss and Bookstein 1982) was obtained from the 109 images (DE 40,EM 29,and MC 40, with approximately equal sex ratios for all stocks). Fourteen landmark coordinates were located per specimen as described by Winans (1984) for Pacific salmon. From these landmarks, 31 morphometric characters (distances) were calculated from six regions (network cells) of the body (Strauss and Bookstein 1982;Figure 3).…”

Research on Captive Broodstock Programs for Pacific Salmon; Assessment of Captive Broodstock Technologies, Annual Report 2002-2003.

“…Cartesian coordinate information for 19 landmarks was collected from each image with the digitizing program tpsDig . Thirty-two distance measurements were calculated between 15 landmarks in a truss network pattern (see Figure 2, after Winans 1984). Landmarks at the anterior tip of the dorsal and anal fins, and at the insertion and distal point of the left pectoral fin were digitized for dorsal and anal fin height, and pectoral fin length, respectively.…”