Arnold Ammann

Current position: Staff Fisheries Researcher, Fisheries Ecology Division, NOAA National Marine Fisheries Service, Santa Cruz Lab

Southwest Fisheries Science Center
100 Shaffer Rd.
Santa Cruz, CA 95060
(831) 420-3968



BA, Aquatic Biology, University of California at Santa Barbara
MA, Biology, University of California at Santa Cruz  (2001)

Research Interests

I have been working in the Salmon Ecology Team of NMFS since 2002. We seek to understand salmonid biology from freshwater to the ocean with the goal of identifying factors that influence survival and movement. This research is examining how behavior, habitat alteration, climate variation, and biological factors are influencing the survival of these fishes. Using acoustic transmitters and arrays of receivers we estimate survival and movement of juvenile Chinook salmon and steelhead as they emigrate from there natal grounds (hatcheries) to the Pacific Ocean. In the ocean we examine condition, growth, and habitat conditions in ship based surveys of juvenile salmon soon after entering the ocean (June) and after about 3 months in the ocean (September). Our research shows that in a typical year the condition of juveniles improves significantly in the first three months of ocean life. We are developing factors important to juvenile salmon that can be used to predict abundance of adults in the fishery. This information is important to managers of the salmon fishery.

Graduate Research at the RC Lab

I studied the recruitment dynamics of nearshore rockfishes in the genus Sebastes. Specifically I examined the spatial and temporal patterns of settlement and how these patterns are related to environmental variables. To facilitate this research I developed a method for quantifying settlement using standard monitoring units for recruitment of fishes or SMURFs. These are artificial habitat units that allow an estimate of relative settlement of rockfish prior to significant post-settlement losses that occur in natural settlement habitat (i.e. kelp forests). SMURFs are great for obtaining very frequent estimates of settlement, for example on a daily or weekly basis.

Besides demonstrating the research value of SMURFs, my graduate work suggests that two groups of rockfish species settle at different times and these patterns are related to environmental conditions. The group including copper, gopher, black and yellow, and kelp rockfish settle in response to ‘relaxation’ conditions, which occur when upwelling winds subside and warmer offshore water moves toward shore. Another group including black, yellowtail, and olive rockfish settle in response to ‘upwelling’ conditions, which occur when northwestern winds cause upwelling of deep cool water along the coast. In Monterey Bay, upwelling occurring just north of the bay, creates a plume of cold water that travels south across the mouth of the bay until it reaches the Monterey Peninsula. When this cold plume reached the site with SMURFs is when I observed the BYO rockfish settling.

Selected Publications

Sean A. Hayes, Morgan H. Bond, Chad V. Hanson, Andrew W. Jones, Arnold J. Ammann, Jeffrey A. Harding, Alison L. Collins, Jeffrey Perez, R. Bruce MacFarlane. Down, up, down and “smolting” twice? Seasonal movement patterns by juvenile steelhead (Oncorhynchus mykiss) in a coastal watershed with a bar closing estuary. Canadian Journal of Fisheries and Aquatic Sciences, Published on the web 27 July 2011, 10.1139/f2011-062

Jeffrey A. Harding, Arnold J. Ammann, R. Bruce MacFarlane 2011. Regional and seasonal patterns of epipelagic fish assemblages from the central California Current. Fish Bulletin. 109(3): 261-281.

Hayes, S.A., Bond, M.H., Hanson, C.V., Freund, E.V., Smith, J.J., Anderson, E.C., Ammann A.J., & MacFarlane R.B. 2008. Steelhead growth in a small central California watershed: Upstream and estuarine rearing patterns. Transactions of the American Fisheries Society 137(1):114-128.

Ammann, A.J. 2004 SMURFs: standard monitoring units for the recruitment of temperate reef fishes. J. Exp. Mar. Bio. Ecol. 299:135-154.

Ammann, A.J. and Carr, M.H. 2000. In: Ecosystem Observations for the Monterey Bay National Marine Sanctuary: Contrasting effects of La Nina and El Nino on recruitment of juvenile rockfish. pp.11-12