A Risk-Based Predictive Tool to Prevent Accidental Introductions of Nonindigenous Marine Species

Abstract

Preventing the introduction of nonindigenous species (NIS) is the most efficient way to avoid the costs and impacts of biological invasions. The transport of fouling species on ship hulls is an important vector for the introduction of marine NIS. We use quantitative risk screening techniques to develop a predictive tool of the abundance and variety of organisms being transported by ocean-going yachts. We developed and calibrated an ordinal rank scale of the abundance of fouling assemblages on the hulls of international yacht hulls arriving in New Zealand. Fouling ranks were allocated to 783 international yachts that arrived in New Zealand between 2002 and 2004. Classification tree analysis was used to identify relationships between the fouling ranks and predictor variables that described the maintenance and travel history of the yachts. The fouling ranks provided reliable indications of the actual abundance and variety of fouling assemblages on the yachts and identified most (60%) yachts that had fouling on their hulls. However, classification tree models explained comparatively little of the variation in the distribution of fouling ranks (22.1%), had high misclassification rates (approximately 43%), and low predictive power. In agreement with other studies, the best model selected the age of the toxic antifouling paint on yacht hulls as the principal risk factor for hull fouling. Our study shows that the transport probability of fouling organisms is the result of a complex suite of interacting factors and that large sample sizes will be needed for calibration of robust risk models.

The Invasive Species Challenge in Estuarine and Coastal Environments: Marrying Management and Science

“…All of the research needs discussed above fold into formal risk assessments, and the lack of data in many cases explains why there have been so few formal risk analyses for coastal and estuarine species Floerl et al 2005). Canada's Centre of Expertise for Aquatic Risk Assessment is advancing risk assessment by standardizing risk assessments for fisheries and invasive species (Canadian Government 2003).…”

Marine biosecurity: protecting indigenous marine species

“…103 This enables staff with minimal taxonomic expertise and training in the approach, to distinguish from a brief visual inspection of the hull from the surface, between vessels that carry, no, sparse or extensive fouling on their hulls. The staff member can then allocate each vessel a rank of 0-5 on arrival and those with a fouling rank of .2 (ie, small patches of macrofouling), can then be subject to further biosecurity measures.…”

Recreational boats as potential vectors of marine organisms at an invasion hotspot

“…Level of fouling (LoF) surveys. At each of the 6 marinas, all vessels moored on the day of sampling were assessed using the LoF ranking system developed by Floerl et al (2005a). This method involves designating a rank of biofouling to each vessel based on an assessment of visible biofouling from above the water.…”

“…Visscher 1928, WHOI 1952, Gollasch 2002), but recreational craft have come under greater scrutiny in the last decade. Recent studies of recreational boats have characterized organism transfers in a few regions of the world including New Zealand, northeastern Australia, the east coast of North America, and European coasts (Floerl & Inglis 2005, Floerl et al 2005a,b, Ashton et al 2006, Minchin et al 2006, Mineur et al 2008, Darbyson et al 2009. Other studies of NIS incursions of bays without commercial ports have also provided indirect evidence for NIS transfers by recreational boats (Carlton 1979, Wasson et al 2001, Cohen et al 2005.…”

“…As a first step in characterizing this vector on the US West Coast, we conducted hull sampling at a subset of marinas in SF Bay and distributed a questionnaire to boaters to evaluate (1) extent and composition of biofouling on vessels and (2) hull maintenance and voyage history patterns among boaters. We also evaluated a ranking system developed by Floerl et al (2005a) and assigned ranks to over 1200 boats. We used these data to categorize recreational vessels according to biofouling levels, vessel behavior, and risk of NIS spread.…”