Showing papers by "Jonathan W. Moore published in 2019"

Genetics of century-old fish scales reveal population patterns of decline

Abstract: Conservation scientists rarely have the information required to understand changes in abundance over more than a few decades, even for important species like Pacific salmon. Such lack of historical information can underestimate the magnitude of decline for depressed populations. We applied genetic tools to a unique collection of 100‐year‐old salmon scales to reveal declines of 56%–99% in wild sockeye populations across Canada's second largest salmon watershed, the Skeena River. These analyses reveal century‐long declines that are much greater than those based on modern era abundance data, which suggested that only 7 of 13 populations declined over the last five decades. Populations of larger‐bodied fish have declined the most in abundance, likely because of size‐selective commercial fisheries. Our findings illustrate how a deep historical perspective can expand our understanding of past abundances to a time before species incurred significant losses from fishing, and help inform conservation for diminished populations.

Estuary habitat associations for juvenile Pacific salmon and pelagic fish: Implications for coastal planning processes

Abstract: Aquatic Conserv: Mar Freshw Ecosyst. 2019;1–21. Abstract 1. Assessment of risk from industrial developments often relies on simple habitat descriptions for focal species. However, simple habitat metrics may not be accurate predictors of locations that species actually use. Understanding the nature of habitat is particularly pressing for estuaries, as they are among the most degraded ecosystems globally but provide critical rearing habitat for many species, including Pacific salmon.

The Role of Science in Contemporary Canadian Environmental Decision Making: The Example of Environmental Assessment

Abstract: In this article, we examine the role of science in Canada’s federal environmental assessment (EA) regime to illustrate opportunities for improvement. We do not address the application of science in EA practices (i.e., how to do good science within EA processes), which has been thoroughly reviewed by others. Instead, we examine the context for science in EA law: we examine the components of a regulatory regime, enshrined by law, that would allow for scientifically defensible assessments and evidence-based decision making. We have four objectives: (1) to provide a recent history of the role(s) of science in Canada’s legislated EA regimes, including public support for science in EA law; (2) to propose five components necessary in an EA regime to ensure strong inclusion of science; (3) to evaluate if new proposed legislation meets scientific standards for modern EA, particularly cumulative effects and climate change; and (4) to encourage collaboration between scholars and practitioners in law and the natural and social sciences to work towards stronger scientific foundations in Canada’s EA regimes at all levels.

Linking anglers, fish, and management in a catch-and-release steelhead trout fishery

Abstract: Fisheries are complex social–ecological systems with multiple potential linkages between fish and anglers. Understanding these linkages helps to support effective fisheries management. We examine t...

Salmon egg subsidies and interference competition among stream fishes

Abstract: Resource availability may modulate interference interactions among competitors. For example, competition among stream fishes for drifting eggs from salmon (Oncorhynchus spp.) spawning events may be influenced by the availability of this energy-rich food source. This study used camera-based techniques to evaluate the effect of varied prey availability (i.e., pink salmon (O. gorbuscha) eggs) on rates of interference competition within natural stream fish communities at 10 sites. Aggressive interactions were quantified across different levels of egg additions, ranging from 6 to 3575 O. gorbuscha eggs, at 10 sites on the Keogh River, British Columbia, Canada. There were fewer aggressive interactions among salmonids (O. kisutch, O. mykiss, and O. clarkii clarkii) when there were more available eggs. Aggressive interaction rates were species-dependent; for example, the number of aggressive acts relative to null expectations based on abundances were highest in juvenile coho (O. kisutch) towards conspecifics. For some interactions, size of fish appeared to be a key factor as well. Thus, higher densities of spawning salmon in streams may provide sufficient prey resources in the form of eggs to temporarily decrease interference competition among stream fishes.

Integrating prey dynamics, diet, and biophysical factors across an estuary seascape for four fish species

Abstract: Estuary food webs support many fishes whose habitat preferences and population dynamics may be controlled by prey abundance and distribution. Yet the identity and dynamics of important estuarine prey of many species are either unknown or highly variable between regions. As anthropogenic development in estuaries increases, so does the need to understand how these environments may be supporting economically, culturally, and ecologically important fishes. Here, we examine how important estuary fishes integrate their prey across the seascape and what may influence prey dynamics. Specifically, we surveyed juvenile coho salmon Oncorhynchus kisutch, juvenile sockeye salmon O. nerka, Pacific herring Clupea pallasii, and surf smelt Hypo mesus pretiosus diets along with zooplankton abundance in the estuary of the Skeena River (British Columbia, Canada) at a relatively fine scale. We found diets were highly variable, even within a species, but 1 or 2 prey composed most diet contents per species. Juvenile coho salmon primarily consumed terrestrial insects and larval fish, whereas sockeye salmon primarily consumed harpacticoid copepods. In contrast, small pelagic fish (Pacific herring and surf smelt) primarily consumed calanoid copepods, which were the most abundant prey in the environment. We found that certain prey groups were correlated with biophysical factors. For example, calanoid copepod abundance was positively correlated with salinity, whereas harpacticoid copepod abundance was highest over eelgrass sites. Identifying key prey species and how they distribute within the estuary seascape is an integral link in understanding the food-web foundation of fish habitat use in areas under pressure from anthropogenic development.

Urban planning for fishes: untangling a new project’s effects from old infrastructure and regional patterns

Abstract: Urbanization has altered fish communities in many ways. However, as cities expand and redevelop, it is challenging to assess the impacts of new projects given existing alteration. We investigated how new and old infrastructure alters fish communities over a 4-year period in Metro Vancouver, British Columbia (Canada). We compared fish communities from a stream altered by a new rapid transit rail line and seven reference sites over 4 years, from before to after construction. We provide evidence that new and old projects depress the density, species richness, and diversity of fish communities. During and after construction, sections of the altered stream had one fewer species and lower density compared with preconstruction and reference streams. Streams without existing culverts had more species and greater diversity than those with culverts, but only in some years. Diversity was lower in 1 year of the study across all streams. We argue that most monitoring in Canada is insufficient to detect the incremental...