TY - JOUR

T1 - Vertical migrations of fish schools determine overlap with a mobile tidal stream marine renewable energy device

AU - Whitton, Timothy

AU - Jackson, Suzie

AU - Hiddink, Jan Geert

AU - Scoulding, Ben

AU - Bowers, David

AU - Powell, Ben

AU - D'Urban Jackson, Tim

AU - Gimenez Noya, Luis

AU - Davies, Alan

PY - 2020/4/1

Y1 - 2020/4/1

N2 - 1. Large increases in the generation of electricity using marine renewable energy (MRE) are planned, and assessment of the environmental impacts of novel MRE devices, such as kites, are urgently needed. A first step in this assessment is to quantify overlap in space and time between MRE devices and prey species of top predators such as small pelagic fish.2. Here, we quantify how the distribution of fish schools overlap with the operational depth (20–60 m) and tidal current speeds (≥ 1.2 – 2.4 m s-1) used by tidal kites, and the physical processes driving overlap. 2. Fish schools undertake diel vertical migrations driven by the depth of light penetration into the water column, controlled by the supply of solar radiation and water column light absorption and scattering, which in turn depends on the cross-sectional area of suspended particulate matter (SPM). Fish schools were found shallower in the morning and evening and deeper in the middle of the day when solar radiation is greatest, with the deepest depths reached during predictable bimonthly periods of lower current speeds and lower cross-sectional area of SPM.4. Potential kite operations overlap with fish schools for a mean of 5% of the time that schools are present (maximum for a day is 36%). This represents a mean of 6% of the potential kite operating time (maximum for a day is 44%). These were both highest during a new moon spring tide and transitions between neap and spring tides. 5. Synthesis and applications. Overlap of fish school depth distribution with tidal kite operation is reasonably predictable, and so the timing of operations could be adapted to avoid potential negative interactions. If all interaction between fish schools was to be avoided, the loss of operational time for tidal kites would be 6%. This information could also be used in planning the operating depths of marine renewable energy (MRE) devices to avoid or minimise overlap with fish schools and their predators by developers, and for environmental licencing and management authorities to gauge potential ecological impacts of different MRE device designs and operating characteristics.

AB - 1. Large increases in the generation of electricity using marine renewable energy (MRE) are planned, and assessment of the environmental impacts of novel MRE devices, such as kites, are urgently needed. A first step in this assessment is to quantify overlap in space and time between MRE devices and prey species of top predators such as small pelagic fish.2. Here, we quantify how the distribution of fish schools overlap with the operational depth (20–60 m) and tidal current speeds (≥ 1.2 – 2.4 m s-1) used by tidal kites, and the physical processes driving overlap. 2. Fish schools undertake diel vertical migrations driven by the depth of light penetration into the water column, controlled by the supply of solar radiation and water column light absorption and scattering, which in turn depends on the cross-sectional area of suspended particulate matter (SPM). Fish schools were found shallower in the morning and evening and deeper in the middle of the day when solar radiation is greatest, with the deepest depths reached during predictable bimonthly periods of lower current speeds and lower cross-sectional area of SPM.4. Potential kite operations overlap with fish schools for a mean of 5% of the time that schools are present (maximum for a day is 36%). This represents a mean of 6% of the potential kite operating time (maximum for a day is 44%). These were both highest during a new moon spring tide and transitions between neap and spring tides. 5. Synthesis and applications. Overlap of fish school depth distribution with tidal kite operation is reasonably predictable, and so the timing of operations could be adapted to avoid potential negative interactions. If all interaction between fish schools was to be avoided, the loss of operational time for tidal kites would be 6%. This information could also be used in planning the operating depths of marine renewable energy (MRE) devices to avoid or minimise overlap with fish schools and their predators by developers, and for environmental licencing and management authorities to gauge potential ecological impacts of different MRE device designs and operating characteristics.

KW - Minesto

KW - SEACAMS

KW - marine renewable energy

KW - Sprat

KW - Acoustics

U2 - 10.1111/1365-2664.13582

DO - 10.1111/1365-2664.13582

M3 - Article

VL - 57

SP - 729

EP - 741

JO - Journal of Applied Ecology

JF - Journal of Applied Ecology

SN - 1365-2664

IS - 4

ER -