Aspects of Embryonic and Larval Development in Bighead Carp Hypophthalmichthys nobilis and Silver Carp Hypophthalmichthys molitrix

Amy E George,Duane C Chapman,Howard I Browman

doi:10.1371/journal.pone.0073829

Abstract

As bighead carp Hypophthalmichthys nobilis and silver carp H . molitrix (the bigheaded carps) are poised to enter the Laurentian Great Lakes and potentially damage the region’s economically important fishery, information on developmental rates and behaviors of carps is critical to assessing their ability to establish sustainable populations within the Great Lakes basin. In laboratory experiments, the embryonic and larval developmental rates, size, and behaviors of bigheaded carp were tracked at two temperature treatments, one “cold” and one “warm”. Developmental rates were computed using previously described stages of development and the cumulative thermal unit method. Both species have similar thermal requirements, with a minimum developmental temperature for embryonic stages of 12.1° C for silver carp and 12.9° C for bighead carp, and 13.3° C for silver carp larval stages and 13.4° C for bighead carp larval stages. Egg size differed among species and temperature treatments, as egg size was larger in bighead carp, and “warm" temperature treatments. The larvae started robust upwards vertical swimming immediately after hatching, interspersed with intervals of sinking. Vertical swimming tubes were used to measure water column distribution, and ascent and descent rates of vertically swimming fish. Water column distribution and ascent and descent rates changed with ontogeny. Water column distribution also showed some diel periodicity. Developmental rates, size, and behaviors contribute to the drift distance needed to fulfill the early life history requirements of bigheaded carps and can be used in conjunction with transport information to assess invasibility of a river.

Highlights

Bighead carp Hypophthalmichthys nobilis (Richardson) and silver carp H. molitrix (Valenciennes, the bigheaded carps) are invasive species in North American waterways, and are currently poised to enter the Laurentian Great Lakes, where they could damage a fishery valued at $7 billion annually in the United States portion alone [1,2]
Each temperature treatment consisted of 10 aquaria that were each equipped with a modified MacDonald hatching jar (45 cm tall and 13 cm internal diameter) and a small submersible pump to recirculate water from the aquarium into the hatching jar, and to provide an upwelling current to keep the eggs suspended in the water column within the jar
Though there are a number of critiques of Cumulative Thermal Units (CTU) methods [23,24], Hamel et al [25,26] found the CTU method to predict incubation times with sufficient accuracy for most fishery management needs

Summary

Introduction

Bighead carp Hypophthalmichthys nobilis (Richardson) and silver carp H. molitrix (Valenciennes, the bigheaded carps) are invasive species in North American waterways, and are currently poised to enter the Laurentian Great Lakes, where they could damage a fishery valued at $7 billion annually in the United States portion alone [1,2]. Larval behavior and swimming capacity, information which is vital for modeling larval dispersal [5], are sparsely documented [6,7]. In their native systems, bigheaded carps normally live and feed in floodplain lakes and low water velocity areas, but they spawn in turbulent portions of large rivers [3]. While ecological effects of establishment are most likely to be experienced in the lake environment, the adequacy of available spawning rivers is highly important in determining the invasibility of the Great Lakes Basin by bigheaded carps

Methods

Results

Conclusion