Ships and Midshipman Fish: Does boat noise influence aggression in a highly vocal fish?

Mackenzie Woods, Kat Nikolich, Nick Brown, Francis Juanes

Department of Biology, University of Victoria

Noise pollution is a growing concern, both on land and underwater.

Anthropogenic (human-generated) noise changes the natural soundscape. Ambient noise levels in the open ocean have doubled every decade since the 1950s1_{. Noise pollution is negatively impacting diverse aquatic species;}

however, the research of its impacts on fish is not yet extensive2_.

Many fishes rely on sound. All fish species have the ability to detect sound;

soniferous fish can also produce sound, making them more reliant on sound

reception and acoustic communication. Anthropogenic noise can disrupt vital communication, mask environmental cues, and lead to physiological &

behavioural changes2,3_.

Soniferous male plainfin midshipman fish (Porichthys notatus) produce several vocalizations, including an advertisement ‘hum’ to attract females, and

defensive ‘grunts’ and ‘growls’. Midshipman ‘guarder’ males take up nests in the intertidal zone to spawn and care for their offspring until they hatch by

defending their nest from egg predators such as shore crabs.

• Each fish (N = 18) was housed in a separate tank with its

own artificial nest (fig. 1, 3) • Nest-invader threat stimulus

(fig. 2)

• Each fish experienced both experimental treatments:

o Boat noise (Treatment) o No noise played (Control) • Filmed trials using GoPro

camera in nest

• Scored aggressive behaviours and movements from videos

Nest-guarding plainfin midshipman males will exhibit increased

aggressive behaviour in the presence of boat noise compared to

ambient conditions

Figure 2. Crab on a rod as the threat stimulus.

Figure 3. Guarder-male in his nest.

Increased aggressive behaviours, in particular lunge frequency, in the noise treatment

suggests boat noise might influence aggression in nest-guarding plainfin midshipman. This

result is consistent with other studies that have found boat noise impacts territoriality and

aggression in other species of fish4_.

Unnecessary aggression and alertness are energetically costly. In addition to directly

affecting individual fitness, excessive alertness could take time that would otherwise be spent on mate attraction and parental care, resulting in diminished reproductive success. Thus,

anthropogenic noise has the potential to

negatively impact plainfin midshipman at the population level.

Figure 8. Plainfin midshipman fish in a nest and being collected in the intertidal.

Literature Cited

1. McDonald, M. A., Hildebrand, J. A. & Wiggins, S. M. Increases in deep ocean ambient noise in the Northeast Pacific west of San Nicolas Island, California. J. Acoust. Soc. Am. 120, 711–718 (2006).

2. Cox, K., Brennan, L. P., Gerwing, T. G., Dudas, S. E. & Juanes, F. Sound the alarm: A meta-analysis on the effect of aquatic noise on fish behavior and physiology. Glob. Change Biol. 24, 3105–3116 (2018).

3. Slabbekoorn, H. et al. A noisy spring: the impact of globally rising underwater sound levels on fish. Trends Ecol. Evol. 25, 419–427 (2010).

4. Sebastianutto, L., Picciulin, M., Costantini, M. & Ferrero, E. A. How boat noise affects an ecologically crucial behaviour: the case of territoriality in

Gobius cruentatus (Gobiidae). Environ. Biol. Fishes 92, 207–215 (2011).

Acknowledgements

Thanks to Noah Houpt, Kieran Cox, UVic Aquatics staff, and other members of the Juanes Lab for their help on this project.

This research is sponsored by the NSERC Canadian Healthy Oceans Network and its Partners: Department of Fisheries and Oceans Canada and INREST (representing the Port of Sept-Îles and City of Sept-Îles).

Figure 5. Plainfin midshipman fry.

Figure 6. Plainfin midshipman

exhibiting frontal fin display towards the crab.

The sum of all aggressive behaviours (i.e. lunges, bites, frontal fin display, and vocalizations)

exhibited by each fish were higher in the noise treatment compared to the control treatment.

Figure 4. The number of times each fish performed each of four aggressive behaviours towards the crab: lunging, biting, frontal fin display, and vocalizing, presence and absence of boat noise.

Likelihood ratio test:

χ²

= 3.70, p-value = 0.05 (N = 9)

Likelihood ratio test:

χ²

Figure 7. Experimental tank.

Mackenzie Woods, Department of Biology

March 5, 2019

This research was supported by the Jamie Cassels Undergraduate

Research Awards, University of Victoria