Long‐term effect of a tidal, hydroelectric propeller turbine on the populations of three anadromous fish species

Abstract

Tidal hydroelectric power has been proposed as one potential solution for sustainable energy sources. The first tidal turbine in North America began continuous operation in the Annapolis River estuary (44 °45'N; 65° 29'W) in June, 1985. The machine is an axial-flow, hydraulic-lift propeller turbine, a type known to cause fish mortality. Anadromous populations of American shad Alosa sapidissima, striped bass Morone saxatilis and Atlantic sturgeon Acipenser oxyrinchus utilize the Annapolis River for spawning and other life history phases. After power generation commenced obvious turbine mortalities of these fishes began appearing downstream of the turbine. Assessments of the A. sapidissima adult spawning runs during 1981-1982 (pre-operation) and 1989-1996 (operational) indicated significant changes in population characteristics after power generation began. Adult length, mass, age and per cent repeat spawners declined and total instantaneous mortality (Z) increased from 0.30 to 0.55. The pre-turbine spawning runs had older fish with numerous adult cohorts whereas by 12 years after operation began runs consisted of younger fish with fewer adult cohorts. During 1972-1987 numerous studies indicated the Annapolis River had an important angling fishery for M. saxatilis, but detailed annual records kept by a fishing contest during 1983-1987 and an elite angler family during the period 1976-2008 demonstrated a rapid decline in the number of fish >4.0 kg after turbine operation began. Pre-turbine catch by the angling family of fish >4.0 kg accounted for 84.1% of total catch, but declined significantly to 39.6% of total catch from 1986-1999, and to none from 2000-2008. The existence of an A. oxyrinchus stock in the Annapolis River was unknown before turbine operation, but during 1985-2017, 21 mortalities were recovered by chance seaward of the turbine. Mechanical strike and cavitation mortalities consisted of juveniles, mature males and gravid and spent females of ages 10 to 53 years found during June to October, the period when this anadromous species returns to its natal river to spawn. The results of the long-term studies at Annapolis indicate managers should realize substantial risks exist for the fish resources of the world's oceans from deployment of instream propeller turbines.

Characterizing Sockeye Salmon Smolt Interactions with a Hydrokinetic Turbine in the Kvichak River, Alaska

“…Therefore, future work should be conducted to assess the fisheries' interactions with multiple devices, which has been highlighted as a future need and direction for hydrokinetic energy projects (Dadswell et al. 2018; Copping et al. 2021).…”

“…Furthermore, this research did not monitor the presence of other anadromous and resident fish species that may encounter the turbine during other (unmonitored) periods of the year. Therefore, future work should be conducted to assess the fisheries' interactions with multiple devices, which has been highlighted as a future need and direction for hydrokinetic energy projects (Dadswell et al 2018;Copping et al 2021).…”

Atlantic sturgeon presence in a designated marine hydrokinetic test site prior to turbine deployment: A baseline study

“…This study is the first to provide baseline information concerning Atlantic sturgeons use of a future tidal energy site. This information is important to management because many sturgeons from endangered and threatened populations from Canada and the USA migrate through MP to enter MB to feed during 10–15 years of their juvenile life (Dadswell et al, 2016, 2018). Our results indicated that Atlantic sturgeon passed through the FORCE sites during May to Nov when they enter or leave MB, travelling pelagically in MP at a depth similar to proposed seabed mounted MHKs (Stokesbury et al, 2016; FORCE 2020).…”

Diversity, abundance and size structure of fishes and invertebrates captured by an intertidal fishing weir at Bramber, Minas Basin, Nova Scotia

“…The information on diversity and abundance will be useful for future comparisons if there are changes in these characteristics of Minas Basin fishes caused either by tidal power development impact or exploitation. Also, the detailed length structure provided for each species will provide sufficient data for significant statistical comparisons in the future if the size structure of individual fish species is altered by propeller turbine mortality removing larger individuals (Dadswell et al 2018) or overexploitation. All these comparisons will be important for assessing any future impact of tidal energy development in the inner Bay of Fundy.…”