ABSTRACT

One of the greatest threats to the recovery of the highly depleted North Atlantic right whale (Eubalaena glacialis) is collisions with ships (or “ship strikes”).  The U.S. National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service (NMFS) has taken a number of steps to reduce the threat, including issuing a final rule (73 Federal Register 60173, October 2008) that requires vessels >65 feet in length to travel at 10 knots or less in certain times and locations (termed “Seasonal Management Areas”, or SMA) of right whale occurrence.  NMFS also initiated a program whereby “Dynamic Management Areas” (DMA) are established in areas in which right whales are observed outside SMAs, whereby temporary zones are created and vessels are requested (but, not required) to either navigate around the zone or travel through it at 10 knots or less.  This process allows for management measures that are tied directly to the known, but perhaps transitory, presence of right whales, and provides a means to establish areas effecting vessel operations that are smaller (in area) and shorter (in duration) than seasonal management measures.  NMFS is monitoring the effectiveness of the restrictions by assessing compliance with the vessel speed limits as well as adherence to associated voluntary measures.  Automatic Identification System (AIS) technologies provide a precise and easily accessible means to do so.

        Originally conceived as a safety of navigation technology, the AIS uses Global Positioning System (GPS)-linked, very high frequency (VHF) radio signal that provides for ship-to-ship and ship-to-shore information transfer.  It transmits the ship’s name, call sign, position, dimensions, speed, heading and other information multiple times each minute.  The AIS signal provides a suite of information, both dynamic (that is unique to a particular voyage) and static (that is consistent for a given vessel).  Dynamic information includes the vessel’s position, speed over ground, course over ground, heading, rate of turn, and position accuracy (< or > 10 m) which are determined by continuous GPS-linked updates.  Static information includes the vessel’s:  name, call sign, type, cargo, and its Maritime Mobile Service Identity (MMSI) number. Given the rate at which it provides this information, AIS is a precise means to remotely track vessel speeds and other vessel operations.

Our goal here is to provide (a) a characterization of vessel traffic volume, patterns, and speeds of vessels transiting SMAs, and (b) an initial assessment of vessel adherence to the vessel speed restrictions.  This summary is for the period of January 2009 (the rule was enacted December 2008) through December 2009.  We also provide an initial characterization of vessel use of DMAs in the same period.

We gathered information on vessel activity in 10 operational SMAs, and in 18 DMAs for the period January to December 2009.  As set forth in the rulemaking, the SMAs we analyzed were effective in: Cape Cod Bay (1 January – 15 May); an area Off Race Point, MA (1 March – 30 April); an area in the Great South Channel (1 April – 31 July); an area extending from mid-coastal Georgia to northern Florida (15 November – 15 April); and (1 November – 30 April for each of the following) Block Island Sound, port entrances of New York City and New Jersey, Philadelphia, PA, Norfolk VA, Wilmington, NC, and an area extending from Wilmington, NC to just south of Savannah, GA.

A total of 39,615 vessel transits were recorded in active SMAs in 2009.  Of these, 10,982 were not applicable to conditions set forth in the Rule or were deemed inaccurate and were therefore removed from further analysis.  Thus, a total of 28,633 transits were analyzed to determine vessel types, vessel speeds, SMA use, and other characteristics of these passages.

The New York-New Jersey port entrance SMA had the greatest number of transits (n = 7,651) followed by the North Carolina-Georgia complex and the Norfolk SMAs (6,502 and 4,790 transits, respectively).  Cargo vessels constituted the majority of ship passages in all SMAs, comprising over 50.3 % of all vessel transits, (and excluding the “other” vessel type category) followed by tanker vessels (14.9%), and tug-type vessels (10.2%).  Cargo vessels were strongly represented in the New York-New Jersey, Norfolk and North Carolina-Georgia SMAs, with the North Carolina-Georgia complex having the highest number of cargo transits of all SMAs.  Considering all transits in all active SMAs the ratio of foreign flagged to domestic vessels was 1.6:1

The most common maximum speed represented was 11 knots; and the majority of all transits were between 11 and 16 knots.  A substantial number of transits were at maximum speeds in excess of 16 knots.  Aggregate maximum speeds in most SMAs exhibited a “bell-curve” with peaks between 10 and 16 knots; while the most highly represented maximum speed in nearly all SMAs was 11 - 12 knots.  Generally, domestic vessels had lower aggregate vessel speeds than did foreign-flagged vessels; foreign-flagged vessels tended to travel at 12 knots or greater.  Cargo vessels exhibited the highest aggregate maximum speeds (with the most traveling in the 15-16 knot range), followed by tankers (with peaks in the 11-13 knot range), and aggregate speeds for passenger vessels had peaks around 12 knots.  Vessels in the “tug, tow, dredge”, and “other” categories exhibited peak aggregate speeds around 10 knots. 

In 2009, 18 DMAs were “triggered” by right whale presence, all occurring in waters off New England.  A total of 1,406 vessel transits occurred in these active DMAs.  The majority were tankers (n = 521), nearly twice as many as any other vessel category.  Excluding the “other” category, cargo vessels were the second most common type.  The distribution of vessel speeds through DMAs is different than the distribution for vessel speeds utilized in SMAs (it was not a “bell-shape” as in the SMA speed distributions).  In DMAs, 11 knots was the most common maximum speed; and there appeared to be a higher proportion of vessels traveling 11 knots or less than those vessels traversing SMAs.  A second peak occurred at 14 knots with a large portion traveling at 13 and 14 knots; probably reflecting the number of cargo ships and tankers traversing the zones.  Likely, many tug and barges and “big-tows” (vessels typically traveling at speeds under 12 knots) have limited options to route around such areas:  being largely coastal and having specific destinations that require routes through DMAs and therefore opt to travel through DMAs; whereas larger, ocean-going vessels on more lengthy routes may have the latitude to avoid a particular area.