Conflicting & Unconclusive Evidence

These quotes are taken straight from the research that NOAA is using to justify this ban. The researchers repeatedly state that their is no conclusive summary they can draw from their observations.

 

RESEARCH SUPPORTING #1

1) From the DEIA

“Johnson et al. (2013) assessed the influence of human activity on the energy budget of Hawaiian spinner dolphins using a theoretical model and comparing predictions from the model to empirical data collected in Kealakekua Bay on spinner dolphin behavior. Under the model, individual dolphins needed to spend at least 60 percent of their time inshore in a resting state to be in a positive energetic balance. Given this assumption, direct observations of spinner dolphins suggest that these animals are currently spending adequate amounts of time engaged in resting behaviors to meet their energetic requirements;

Tyne (2015) found that spinner dolphins were exposed to human activities within 100 m over 80 percent of the time that the dolphins were using essential daytime habitat. Evaluations between control conditions, i.e., no vessels or people within 100 m of dolphins, and exposure conditions, i.e., vessels or people within 100 m of dolphins, suggested that human activities did not have a significant effect on the probability of spinner dolphins engaging in resting, socializing, or traveling. “

2) Effects of vessels and swimmers on behavior of Hawaiian spinner dolphins (Stenella longirostris) in Kealake‘akua, Honaunau, and Kauhako bays, Hawai‘i

SARAH COURBIS, MARINE MAMMAL SCIENCE, **(*): ***–*** (*** 2008) ⃝C 2008 by the Society for Marine Mammalogy   DOI: 10.1111/j.1748-7692.2008.00254.x

“The lack of significant correlation between levels of behavior and traffic may be because there is no relationship, the relationship between them is not linear, or there are motivations for aerial behavior aside from vessels and swimmers.

 Although we cannot directly link the increases in vessel and swimmer traffic in Kealake‘akua Bay to these changes in aerial behavior, it is likely that vessel and swimmer activity is at least synergistically involved in causing these changes. Whether these changes are affecting the survival and fitness of spinner dolphins is unknown.”

Acoustic monitoring could be used to determine if there have been changes in acoustic behavior over time as well since spinner dolphins have been previously recorded in Kealake‘akua Bay (e.g., Watkins and Schevill 1974, Norris et al. 1994).

Although controlled experiments on behavior, such as those described by Bejder and Samuels (2003), are not really possible in the three bays we studied because dolphins are never present without swimmers or vessels, continued opportunistic studies similar to ours, but over longer periods of time, should be conducted.

Also, the largest difficulty in correlating behavior to human activity is the myriad motivations for behavior aside from disturbance. “

 

 

 

 

 

  1. Effects of Human Traffic on the Movement Patterns of Hawaiian Spinner Dolphins (Stenella longirostris)

in Kealakekua Bay, Hawaii

Gregory Timmel,1 Sarah Courbis,2 Holly Sargeant-Green,3 and Hal Markowitz4

 

Aquatic Mammals 2008, 34(4), 402-411, DOI 10.1578/AM.34.4.2008.402

 

 

This study demonstrated weak but significant correlations between human activity-related vari- ables and two different measures of dolphin group movement. The original study design called for a comparison between tracks when human traffic was absent and tracks when different types (e.g., swimmers, kayaks, motor vessels) and different levels of anthropogenic activity were present. This proved impossible because there were no tracks during which swimmers and/or vessels were not adjacent to the dolphin group being observed. Once spinner dolphin groups have descended into rest, their behavior becomes relatively consistent and resistant to change (Norris et al., 1994). This appeared to be the case in this study and may partially explain the decreased statistical significance of some of the correlations reported here. It may also be that since there is a greater intensity of anthropogenic activity in Kealakekua Bay, these dolphins have become more tolerant than those at Midway.

 

 

 

Funded by NOOA and DOLPHINQUEST

 

Tyne, J. A., Pollock, K. H., Johnston, D. W., & Bejder, L. (2014). Abundance and Survival Rates of the Hawai’i Island Associated Spinner Dolphin (Stenella longirostris) Stock. PLoS ONE, 9(1), e86132. http://doi.org/10.1371/journal.pone.0086132

Recent short-term research has suggested that an increase in human traffic inside and outside of the dolphin resting habitats [14], [19], [21] resulted in dolphins spending less time in these resting habitats (e.g. [14]) and that their resting behaviour was interrupted as a consequence. It has been suggested that spinner dolphins may leave the bays in direct response to human interactions [19]–[21], [28]. However, it was not possible to identify population level effects from these short-term studies.

 

  1. MARINE MAMMAL SCIENCE, 25(2): 430–440 (April 2009) Effects of vessels and swimmers on behavior of Hawaiian spinner dolphins (Stenella longirostris) in Kealake‘akua, Honaunau, and Kauhako bays, Hawai‘i

SARAH COURBIS

 

 

2009 by the Society for Marine Mammalogy

DOI: 10.1111/j.1748-7692.2008.00254.x

 

the level of swimmer and vessel traffic alone is insufficient to determine whether dolphins are being impacted by traffic.

 

 

The lack of significant correlation between levels of behavior and traffic may be because there is no relationship, the relationship between them is not linear, or there are motivations for aerial behavior aside from vessels and swimmers. Given the preliminary nature of our study and the small number of observation days we were able to fund, we believe this warrants further research.

 

 

 

  1. J. Mar. Biol. Ass. U.K. (2007), 87, 109–112 doi: 10.1017/S0025315407054148 Printed in the United Kingdom

Hawaiian spinner dolphins and the growing dolphin watching activity in Oahu Fabienne Delfour

 

Hawaiian spinner dolphins (Stenella longirostris) feed offshore at night on mesopelagic prey and move to protected shallow waters in early morning to rest. We hypothesized that this behaviour would make them particularly sensitive to anthropogenic factors in these rest areas and would affect their overall behaviour and their population frequency. To test our hypothesis we collected data in a known rest area along the north-west coast of the island of Oahu during August of 2001, 2002 and 2003. Using land- and water-based surveys, we evaluated dolphin group size, counted boats, kayaks and swimmers in the vicinity of the dolphins (<40 m) and reported any changes in dolphin behaviour. Our results demonstrated a stable dolphin habitat frequency over the three summers, which emphasizes the critical value of this rest area for this spinner dolphin population. The results also showed an increase in dolphin-oriented activities, but we could not draw any definitive conclusion on their real impacts on spinner dolphin ecology and ethology.

Thank you Mirabai Galashan for this information